A high-strength and long-life lubricating coating for space equipment and its application method

Abstract

The present invention relates to the technical field of lubricating coatings, and provides a high-strength, long-life lubricating coating for space equipment and an application method thereof. The lubricating coating comprises the following raw materials in parts by mass: 30 to 50 parts of a mixed solvent, 40 to 60 parts of a polydimethylsiloxane-modified polyamic acid solution, and 10 to 18 parts of molybdenum disulfide; in an atomic oxygen environment, polydimethylsiloxane is oxidized to form SiO x Passivation layer protects the coating. 21 atom / cm 2 After atomic oxygen irradiation, the mass loss of the modified coating is less than half of that of the unmodified coating. When tested in a vacuum environment, the wear life of the coating is greater than 6×10 5 r, has excellent resistance to space environment and improves the on-orbit service life and service stability of the lubricating coating.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating coatings, and in particular to a high-strength and long-life lubricating coating for space equipment and an application method thereof. Background Art

[0002] In low-Earth orbit, spacecraft's moving parts require long-term, stable lubrication while in orbit. With the advancement of aerospace technology, the design service life of spacecraft has been increased to 10-15 years. However, the unique space environment of low-Earth orbit can damage the performance of lubricating materials, causing lubrication failure, resulting in a short service life, low reliability, and even serious flight accidents. Due to the high vacuum, radiation, and atomic oxygen environment in low-Earth orbit, lubricants are prone to creep, volatilization, and decomposition in space machinery, limiting their application.

[0003] Bonded solid lubricating coatings have the characteristics of low evaporation rate, corrosion resistance, wear resistance and friction reduction, and excellent film performance. They are commonly used lubricating materials in space machinery. Among them, polyamide-imide has excellent mechanical properties and is often used in spacecraft. It is also used as a binder for bonded solid lubricating coatings. Polyamide-imide-based bonded solid lubricating coatings have excellent adhesion to the substrate and have excellent friction reduction and anti-wear properties. However, polyamide-imide resins are easily corroded by the atomic oxygen environment in low-Earth orbit, resulting in quality loss and performance degradation of the lubricating coating, and the service life of the coating is seriously reduced. In the design mission of the new generation of spacecraft, higher requirements are placed on the service life of low-Earth orbit. The lubricating coating of space machinery needs to withstand higher doses of atomic oxygen corrosion. The existing polyamide-imide-based bonded solid lubricating coatings are difficult to meet the performance requirements of long-term on-orbit service. Therefore, providing a high-strength, long-life solid lubricating coating with excellent wear resistance and adaptability to the space environment has become a problem that needs to be solved urgently. Summary of the Invention

[0004] The purpose of the present invention is to overcome the problems existing in the prior art and provide a high-strength and long-life lubricating coating for space equipment and an application method thereof.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The present invention provides a polydimethylsiloxane-modified polyamic acid solution, comprising the following raw materials in the following proportions:

[0007] Aminopropyl-terminated polydimethylsiloxane, diamino substances, trimellitic anhydride and mixed solvent;

[0008] The mass ratio of the diamino substance and trimellitic anhydride to the aminopropyl-terminated polydimethylsiloxane is 8 to 10:1;

[0009] The molar ratio of the aminopropyl-terminated polydimethylsiloxane and the diamino substance to trimellitic anhydride is 1:0.95-1.15;

[0010] The mass ratio of the aminopropyl-terminated polydimethylsiloxane, the diamino substance and trimellitic anhydride to the mixed solvent is 1:3-5.

[0011] Preferably, the diamino substance is one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone and ethylenediamine.

[0012] Preferably, the solvent comprises N,N-dimethylformamide and solvent a; the solvent a is xylene or toluene; and the mass ratio of the N,N-dimethylformamide to solvent a is 6 to 8:1.

[0013] The present invention also provides a method for preparing the polydimethylsiloxane-modified polyamic acid solution, comprising the following steps:

[0014] Aminopropyl-terminated polydimethylsiloxane and diamino substances are dissolved in a mixed solvent, and then trimellitic anhydride is added to react to obtain a polydimethylsiloxane-modified polyamic acid solution.

[0015] Preferably, the reaction atmosphere is nitrogen, argon or neon; the reaction temperature is 60-70° C., and the reaction time is 6-8 h.

[0016] The present invention also provides application of the polydimethylsiloxane-modified polyamic acid solution in coatings.

[0017] The present invention also provides a lubricating coating prepared from the following raw materials in parts by mass:

[0018] 30-50 parts of mixed solvent, 40-60 parts of polydimethylsiloxane modified polyamic acid solution, and 10-18 parts of molybdenum disulfide.

[0019] The present invention also provides application of the lubricating coating in a space environment.

[0020] The present invention also provides a method for applying a lubricating coating, comprising the following steps:

[0021] The lubricating coating is sprayed and cured in sequence to obtain a polyamide-imide based bonded solid lubricating coating.

[0022] Preferably, the curing is a first curing and a second curing performed sequentially; the temperature of the first curing is 140-160°C, and the time of the first curing is 0.8-1.2 hours; the temperature of the second curing is 270-290°C, and the time of the second curing is 0.8-1.2 hours.

[0023] The beneficial effects of the present invention are:

[0024] (1) The present invention provides a polydimethylsiloxane modified polyamic acid solution, comprising the following raw materials: aminopropyl-terminated polydimethylsiloxane, diamino substances, trimellitic anhydride and a mixed solvent; the mass ratio of the sum of the mass of the diamino substances and trimellitic anhydride to the mass of aminopropyl-terminated polydimethylsiloxane is 8 to 10:1; the molar ratio of the sum of the moles of aminopropyl-terminated polydimethylsiloxane and diamino substances to the molar ratio of trimellitic anhydride is 1:0.95 to 1.15; the mass ratio of the sum of the mass of aminopropyl-terminated polydimethylsiloxane, diamino substances and trimellitic anhydride to the mass ratio of the mixed solvent is 1:3 to 5. The polydimethylsiloxane modified polyamic acid solution provided by the present invention has excellent atomic oxygen resistance. In an atomic oxygen environment, polydimethylsiloxane will form SiO after being oxidized. x The passivation layer protects the coating. Therefore, after being modified with polydimethylsiloxane, the coating has excellent adaptability to space environment.

[0025] (2) The present invention provides a lubricating coating, which is cured to obtain a polyamide-imide-based lubricating coating. 21 atom / cm 2 After atomic oxygen irradiation, the mass loss is less than half of the unmodified coating, and the coating is -5 Pa vacuum environment, the setting conditions are: dual - GCr15 steel ball with a diameter of 6mm, rotation radius - 5mm, load - 5N, rotation speed - 800rpm, the test results show that the wear life of the coating is greater than 6×10 5 r, has excellent resistance to space environment and improves the on-orbit service life and service stability of the bonded solid lubricant coating. DETAILED DESCRIPTION

[0026] The present invention provides a polydimethylsiloxane-modified polyamic acid solution, comprising the following raw materials in the following proportions:

[0027] Aminopropyl-terminated polydimethylsiloxane, diamino substances, trimellitic anhydride and mixed solvent;

[0028] In the present invention, the mass ratio of the diamino substance and trimellitic anhydride to the aminopropyl-terminated polydimethylsiloxane is 8 to 10:1, preferably 8.5 to 9.5:1, and more preferably 8.8 to 9.2:1;

[0029] In the present invention, the molar ratio of the aminopropyl-terminated polydimethylsiloxane and the diamino substance to trimellitic anhydride is 1:0.95-1.15, preferably 1:1.00-1.10, and more preferably 1:1.02-1.08;

[0030] In the present invention, the mass ratio of the aminopropyl-terminated polydimethylsiloxane, the diamino substance and the trimellitic anhydride to the mixed solvent is 1:3-5, preferably 1:3.5-4.5, and more preferably 1:3.8-4.2.

[0031] In the present invention, the molecular weight of the aminopropyl-terminated polydimethylsiloxane is preferably 1000 to 27000 g / mol, more preferably 1500 to 25000 g / mol, and even more preferably 2000 to 20000 g / mol.

[0032] In the present invention, the diamino substance is preferably one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone and ethylenediamine.

[0033] In the present invention, the mixed solvent preferably comprises N,N-dimethylformamide and solvent a; the solvent a is preferably xylene or toluene; the mass ratio of N,N-dimethylformamide to solvent a is preferably 6 to 8:1, more preferably 6.5 to 7.5:1, and more preferably 6.8 to 7.2:1.

[0034] The present invention also provides a method for preparing the polydimethylsiloxane-modified polyamic acid solution, comprising the following steps:

[0035] Aminopropyl-terminated polydimethylsiloxane and diamino substances are dissolved in a mixed solvent, and then trimellitic anhydride is added to react to obtain the polydimethylsiloxane-modified polyamic acid solution.

[0036] In the present invention, aminopropyl-terminated polydimethylsiloxane, a diamino substance and a mixed solvent are mixed at a reaction temperature, and trimellitic anhydride is added under a reaction atmosphere.

[0037] In the present invention, the trimellitic anhydride is preferably added in batches, and the number of times of the addition is preferably 3 to 6 times, more preferably 4 to 5 times.

[0038] In the present invention, the reaction atmosphere is preferably nitrogen, argon, or neon; the reaction is preferably carried out in an oil bath; the reaction temperature is preferably 60-70°C, more preferably 62-68°C, and more preferably 64-66°C; and the reaction time is preferably 6-8 hours, more preferably 6.5-7.5 hours, and more preferably 6.7-7.3 hours.

[0039] The present invention also provides a method for preparing polydimethylsiloxane-modified polyamide-imide, comprising the following steps:

[0040] The polydimethylsiloxane-modified polyamic acid solution is thermally cured to obtain the polydimethylsiloxane-modified polyamide-imide.

[0041] In the present invention, the thermal curing is preferably a first thermal curing and a second thermal curing carried out sequentially; the temperature of the first thermal curing is preferably 140-160°C, more preferably 145-155°C, and more preferably 147-153°C; the time of the first thermal curing is preferably 0.8-1.2h, more preferably 0.9-1.1h, and more preferably 0.95-1.05h; the temperature of the second thermal curing is preferably 270-290°C, more preferably 275-285°C, and more preferably 278-282°C; the time of the second thermal curing is preferably 0.8-1.2h, more preferably 0.9-1.1h, and more preferably 0.95-1.05h.

[0042] The present invention also provides application of the polydimethylsiloxane-modified polyamic acid solution in coatings.

[0043] The present invention also provides a lubricating coating prepared from the following raw materials in parts by mass:

[0044] 30-50 parts of mixed solvent, 40-60 parts of polydimethylsiloxane modified polyamic acid solution, and 10-18 parts of molybdenum disulfide.

[0045] In the present invention, the mass fraction of the mixed solvent is 30 to 50 parts, preferably 35 to 45 parts, and more preferably 38 to 42 parts.

[0046] In the present invention, the mass fraction of the polydimethylsiloxane-modified polyamic acid solution is 40 to 60 parts, preferably 44 to 56 parts, and more preferably 48 to 52 parts.

[0047] In the present invention, the mass fraction of the molybdenum disulfide is 10 to 18 parts, preferably 12 to 16 parts, and more preferably 13 to 15 parts.

[0048] The present invention also provides a method for preparing the lubricating coating, comprising the following steps:

[0049] Molybdenum disulfide is mixed with part of the mixed solvent and ground to obtain molybdenum disulfide slurry; the molybdenum disulfide slurry is evenly mixed with the remaining raw materials to obtain the lubricating coating.

[0050] In the present invention, the mass ratio of the molybdenum disulfide to a portion of the mixed solvent is preferably 1:1-1.5, more preferably 1:1.1-1.4, and even more preferably 1:1.2-1.3.

[0051] The present invention also provides application of the lubricating coating in a space environment.

[0052] The present invention also provides a method for applying a lubricating coating, comprising the following steps:

[0053] The lubricating coating is sprayed and cured in sequence to obtain a polyamide-imide based bonded solid lubricating coating.

[0054] In the present invention, the curing is preferably a first curing and a second curing carried out sequentially; the temperature of the first curing is preferably 140-160°C, more preferably 145-155°C, and more preferably 147-153°C; the time of the first curing is preferably 0.8-1.2h, more preferably 0.9-1.1h, and more preferably 0.95-1.05h; the temperature of the second curing is preferably 270-290°C, more preferably 275-285°C, and more preferably 278-282°C; the time of the second curing is preferably 0.8-1.2h, more preferably 0.9-1.1h, and more preferably 0.95-1.05h.

[0055] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0056] Example 1

[0057] 1 g of aminopropyl-terminated polydimethylsiloxane with a molecular weight of 3000 g / mol and 4 g of 4,4'-diaminodiphenyl ether were added to a three-necked flask, and 36 g of a mixed solvent (N,N-dimethylformamide to xylene mass ratio of 8:1) was added. The aminopropyl-terminated polydimethylsiloxane and diaminodiphenyl ether were dissolved by stirring under nitrogen protection, and the mixture was slowly heated to 65°C in an oil bath. 4 g of trimellitic anhydride was slowly added to the three-necked flask in three portions, and the polymerization reaction was carried out at 65°C for 7 h to obtain a polydimethylsiloxane-modified polyamic acid solution.

[0058] 15 g of molybdenum disulfide was mixed with 18 g of a mixed solvent (the mass ratio of N, N-dimethylformamide to xylene was 8:1) to obtain a molybdenum disulfide slurry, and then 50 g of a polydimethylsiloxane-modified polyamic acid solution was mixed with the molybdenum disulfide slurry, and 40 g of a mixed solvent (the mass ratio of N, N-dimethylformamide to xylene was 8:1) was added, and the mixture was evenly mixed using a high-speed dispersion to obtain a lubricating coating. The coating was then sprayed on the surface of the substrate using a spray gun, first cured at 150°C for 1 hour, and then cured at 280°C for 1 hour to obtain a polyamide-imide-based lubricating coating a.

[0059] A comparative example of this embodiment was set up, with other conditions kept unchanged, and the polydimethylsiloxane-modified polyamic acid solution was replaced with an unmodified polyamic acid solution. The obtained coating was recorded as lubricating coating b.

[0060] Coating a and coating b were subjected to 1.3×10 21 atom / cm 2After irradiation, the mass loss of coating a was measured to be 0.24 mg / cm 2 The mass loss of coating b is 0.57 mg / cm 2 ; When the vacuum degree is less than 5×10 -5 Pa vacuum environment, the setting conditions are: dual-diameter GCr15 steel ball of 6mm, rotation radius-5mm, load-5N, rotation speed-800rpm, the wear life of coating a is 6.15×10 5 r.

[0061] Example 2

[0062] 1 g of aminopropyl-terminated polydimethylsiloxane with a molecular weight of 4000 g / mol and 2 g of ethylenediamine were added to a three-necked flask, and 60 g of a mixed solvent (N,N-dimethylformamide to toluene mass ratio of 7:1) was added. The aminopropyl-terminated polydimethylsiloxane and diaminodiphenyl ether were dissolved by stirring under nitrogen protection, and the mixture was slowly heated to 68°C in an oil bath. 9 g of trimellitic anhydride was slowly added to the three-necked flask in three portions, and the polymerization reaction was carried out at 68°C for 6.5 hours to obtain a polydimethylsiloxane-modified polyamic acid solution.

[0063] 18 g of molybdenum disulfide was mixed with 20 g of a mixed solvent (the mass ratio of N, N-dimethylformamide to toluene was 7:1) to obtain a molybdenum disulfide slurry, and then 55 g of a polydimethylsiloxane-modified polyamic acid solution was mixed with the molybdenum disulfide slurry, and 35 g of a mixed solvent (the mass ratio of N, N-dimethylformamide to toluene was 7:1) was added, and the mixture was evenly dispersed using a high-speed dispersion to obtain a lubricating coating. The coating was then sprayed on the surface of the substrate using a spray gun, first cured at 145°C for 1.1 h, and then cured at 285°C for 0.9 h to obtain a polyamide-imide-based lubricating coating c.

[0064] A comparative example of this embodiment was set up, with other conditions kept unchanged, and the polydimethylsiloxane-modified polyamic acid solution was replaced with an unmodified polyamic acid solution. The obtained coating was recorded as lubricating coating d.

[0065] Coating c and coating d were subjected to 1.3×10 21 atom / cm 2 After irradiation, the mass loss of coating c was measured and the mass loss was 0.21 mg / cm 2 The mass loss of coating d is 0.49 mg / cm 2 ; When the vacuum degree is less than 5×10 -5 Pa vacuum environment, the setting conditions are: pair - GCr15 steel ball with a diameter of 6mm, rotation radius - 5mm, load - 5N, rotation speed - 800rpm, the wear life of coating c is 6.09×10 5 r.

[0066] Example 3

[0067] 0.8 g of aminopropyl-terminated polydimethylsiloxane with a molecular weight of 3500 g / mol and 3.9 g of 4,4'-diaminodiphenyl ether were added to a three-necked flask, and 30.8 g of a mixed solvent (N,N-dimethylformamide to toluene mass ratio of 6.5:1) was added. The aminopropyl-terminated polydimethylsiloxane and diaminodiphenyl ether were dissolved by stirring under nitrogen protection, and the mixture was slowly heated to 62°C in an oil bath. 4.1 g of trimellitic anhydride was slowly added to the three-necked flask in three portions, and the polymerization reaction was carried out at 62°C for 7.5 hours to obtain a polydimethylsiloxane-modified polyamic acid solution.

[0068] 17 g of molybdenum disulfide was mixed with 19 g of a mixed solvent (the mass ratio of N, N-dimethylformamide to toluene was 6.5:1) to obtain a molybdenum disulfide slurry, and then 45 g of a polydimethylsiloxane-modified polyamic acid solution was mixed with the molybdenum disulfide slurry, and 45 g of a mixed solvent (the mass ratio of N, N-dimethylformamide to toluene was 6.5:1) was added, and mixed evenly using a high-speed dispersion to obtain a lubricating coating. The coating was then sprayed on the surface of the substrate using a spray gun, first cured at 155°C for 0.9 h, and then cured at 275°C for 1.1 h to obtain a polyamide-imide-based lubricating coating e.

[0069] A comparative example of this embodiment was set up, with other conditions kept unchanged, and the polydimethylsiloxane-modified polyamic acid solution was replaced with an unmodified polyamic acid solution. The resulting coating was recorded as lubricating coating f.

[0070] Coating e and coating f were subjected to 1.3×10 21 atom / cm 2 After irradiation, the mass loss of coating a was measured to be 0.27 mg / cm 2 , the mass loss of coating f is 0.61 mg / cm 2 ; When the vacuum degree is less than 5×10 -5 Pa vacuum environment, the setting conditions are: pair - GCr15 steel ball with a diameter of 6mm, rotation radius - 5mm, load - 5N, rotation speed - 800rpm, the wear life of coating e is 6.17×10 5 r.

[0071] From the above examples, it can be seen that the present invention provides a lubricating coating, which is cured to obtain a polyamide-imide-based lubricating coating. 21 atom / cm 2 After atomic oxygen irradiation, the mass loss is less than half of the unmodified coating, and the coating is -5Pa vacuum environment, the setting conditions are: dual - GCr15 steel ball with a diameter of 6mm, rotation radius - 5mm, load - 5N, rotation speed - 800rpm, the test results show that the wear life of the coating is greater than 6×10 5 r, has excellent resistance to space environment and improves the on-orbit service life and service stability of the bonded solid lubricant coating.

[0072] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A lubricating coating, characterized in that: Prepared from the following raw materials in parts by weight: 30-50 parts of mixed solvent, 40-60 parts of polydimethylsiloxane modified polyamic acid solution, and 10-18 parts of molybdenum disulfide; The polydimethylsiloxane-modified polyamic acid solution comprises the following raw materials: Aminopropyl-terminated polydimethylsiloxane, diamino substances, trimellitic anhydride and mixed solvent; The mass ratio of the diamino substance and trimellitic anhydride to the aminopropyl-terminated polydimethylsiloxane is 8 to 10:1; The molar ratio of the aminopropyl-terminated polydimethylsiloxane and the diamino substance to trimellitic anhydride is 1:0.95-1.15; The mass ratio of the aminopropyl-terminated polydimethylsiloxane, the diamino substance and the trimellitic anhydride to the mixed solvent is 1:3-5; The mixed solvent comprises N,N-dimethylformamide and solvent a; the solvent a is xylene or toluene; the mass ratio of N,N-dimethylformamide to solvent a is 6 to 8:1; The preparation method of the polydimethylsiloxane modified polyamic acid solution comprises the following steps: Dissolving aminopropyl-terminated polydimethylsiloxane and a diamino substance in a mixed solvent, and then adding trimellitic anhydride to react to obtain a polydimethylsiloxane-modified polyamic acid solution; The reaction temperature is 60-70°C and the reaction time is 6-8h; The reaction atmosphere is nitrogen, argon or neon.

2. The lubricating coating according to claim 1, wherein The diamino substance is one or more of 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl sulfone and ethylenediamine.

3. Use of the lubricating coating according to any one of claims 1 to 2 in a space environment.

4. A method for applying the lubricating coating according to any one of claims 1 to 2, characterized in that: It includes the following steps: The lubricating coating according to any one of claims 1 to 2 is sprayed and cured in sequence to obtain a polyamide-imide-based bonded solid lubricating coating.

5. The application method according to claim 4, characterized in that: The curing includes a first curing and a second curing performed sequentially; the temperature of the first curing is 140-160° C., and the time of the first curing is 0.8-1.2 hours; the temperature of the second curing is 270-290° C., and the time of the second curing is 0.8-1.2 hours.