Aerospace-grade wide-temperature-range anti-radiation lubricating grease and preparation method thereof

Abstract

The invention discloses aerospace-grade wide-temperature-range anti-radiation lubricating grease and a preparation method thereof, and belongs to the technical field of lubricating grease. The perfluoropolyether lubricating oil comprises the following components in parts by weight: 80-85 parts of perfluoropolyether base oil, 12-16 parts of a polytetrafluoroethylene thickening agent, 0.8-1.5 parts of an anti-radiation additive, 1.5-2.5 parts of a nano extreme pressure anti-wear agent and 0.2-0.5 part of an anticorrosive agent. Through innovative design and synergistic effect of a material system, the high-performance lubricating grease which is excellent in three core indexes of wide temperature range, radiation resistance and long service life is successfully developed, the comprehensive technical effect is remarkable, and the blank in the prior art is filled.

Description

Technical Field

[0001] This invention belongs to the field of lubricating grease technology, specifically relating to an aerospace-grade wide-temperature-range anti-radiation lubricating grease and its preparation method. Background Technology

[0002] As human space activities deepen, spacecraft (such as high-orbit satellites, deep space probes, and space stations) face increasingly harsh environments, placing extreme demands on the reliability and long lifespan (often requiring over 15 years of maintenance-free operation) of their critical moving components (such as solar array drive mechanisms, antenna pointing mechanisms, and reaction wheels). The greases used in these components must withstand multiple challenges simultaneously, including extreme high and low temperatures, high vacuum, strong atomic oxygen corrosion, and space particle radiation. However, existing greases cannot fully meet these requirements, exhibiting the following main problems and defects:

[0003] Insufficient radiation resistance: When molecular chains are irradiated by high-energy particles in space (such as electrons and protons), two competing reactions occur: main chain breakage (fracture) and cross-linking (polymerization). In a vacuum, oxygen-free environment, the cross-linking reaction often dominates, leading to increased grease consistency, hardening, or even solidification, a sharp increase in frictional torque, and ultimately, mechanical seizure and failure. Existing greases are generally not specifically formulated for radiation resistance, and their tolerance to cumulative radiation dose is limited (usually <100 kGy), making it difficult to meet the needs of long-life, high-orbit satellites (cumulative doses in geosynchronous orbit can reach hundreds of kGy) and deep space exploration missions.

[0004] Even in extreme environments below -70°C, the starting and running torque of grease may still exceed the design limits of precision mechanisms, posing a risk of jamming. Introducing traditional sulfur-phosphorus-chlorine type extreme pressure anti-wear agents would severely compromise their chemical inertness and high-temperature stability. Therefore, existing formulations have a short wear life when facing high-load, frequent start-stop conditions.

[0005] While additives can achieve good extreme pressure anti-wear properties, they are highly volatile, easily volatilizing and condensing in a vacuum environment, contaminating optical surfaces. Furthermore, they exhibit poor high-temperature oxidation stability, and their operating temperature range falls far short of aerospace requirements. Silicone-based greases possess a wide temperature range and good chemical stability, but their lubrication, particularly boundary lubrication, is poor, offering insufficient protection against wear in steel-to-steel friction pairs. Additionally, they are more prone to cross-linking and curing under high-energy radiation.

[0006] In summary, existing technologies cannot simultaneously maintain the inherent advantages of wide temperature range and low volatility while addressing the performance failure caused by cross-linking and curing under strong radiation environments. Furthermore, there is still room for improvement in torque performance at extreme low temperatures and wear resistance under long-term high loads. A comprehensive lubrication solution that can systematically and synergistically resolve the contradictions between wide temperature range, radiation resistance, long lifespan, and high reliability is lacking. Summary of the Invention

[0007] In view of this, the purpose of this invention is to provide an aerospace-grade wide-temperature-range anti-radiation grease and its preparation method. This invention has inherent high-temperature stability, chemical inertness and anti-radiation potential at the molecular level. By introducing nanomaterials and special additives, it specifically solves the problems of lubrication and long-term service under extreme environments.

[0008] To achieve the above objectives, the present invention provides the following technical solution:

[0009] This invention provides an aerospace-grade wide-temperature-range anti-radiation grease, comprising the following components in parts by weight:

[0010] 80-85 parts of perfluoropolyether base oil

[0011] 12-16 parts of polytetrafluoroethylene thickener

[0012] Radiation-resistant additive: 0.8-1.5 parts

[0013] 1.5-2.5 parts of nano-extreme pressure anti-wear agent

[0014] Corrosion inhibitor 0.2-0.5 parts

[0015] Preferably, the perfluoropolyether base oil has a linear structure and a molecular weight of 3000 to 4000. Linear-chain PPPE has a lower pour point (< -70℃) and is more suitable for a wider temperature range.

[0016] Preferably, the polytetrafluoroethylene thickener is PTFE micro powder with an average particle size of 1~5μm. This thickener is chemically inert, has excellent compatibility with PPPE, is resistant to high and low temperatures, and possesses excellent radiation resistance.

[0017] Preferably, the anti-radiation additive is a compound of phenyl-α-naphthylamine and polycyclic aromatic hydrocarbons, prepared by compounding phenyl-α-naphthylamine and pyrene in a mass ratio of (1:0.5) to (1:2). Phenyl-α-naphthylamine is a highly efficient amine antioxidant / anti-radiation agent; polycyclic aromatic hydrocarbons can effectively absorb and disperse radiation energy, protecting the molecular chains of base oils.

[0018] Preferably, the nano-extreme pressure anti-wear agent is tungsten disulfide nanosheets modified with a perfluoropolyether silane coupling agent.

[0019] Preferably, the corrosion inhibitor is barium perfluorooctyl sulfonate.

[0020] This invention provides a method for preparing the aforementioned aerospace-grade wide-temperature-range anti-radiation grease, comprising the following steps:

[0021] S1. Under stirring conditions, mix 50-70% perfluoropolyether base oil with polytetrafluoroethylene thickener to form a paste;

[0022] S2. Heat the paste and shear it at high speed, while adding the remaining perfluoropolyether base oil, for 60-90 minutes.

[0023] S3. Cool the material and add the radiation-resistant additive, corrosion inhibitor and nano extreme pressure anti-wear agent, and continue to stir and disperse until uniform for degassing treatment.

[0024] According to claim 7, the aerospace-grade wide-temperature-range anti-radiation grease is characterized in that the heating temperature of S2 is 95~105℃.

[0025] Preferably, the high-speed shearing is a shearing rate of 5000~7000 rpm.

[0026] Preferably, the material is cooled to 55~65℃.

[0027] It contains at least the following beneficial technical effects:

[0028] This invention successfully and synergistically solves the problem of long-life lubrication of aerospace greases in ultra-wide temperature ranges and high-radiation environments. Test data clearly show that the overall performance of the grease of this invention is significantly better than that of comparative products lacking key components or using alternative components, fully meeting the needs of future high-end aerospace missions. Detailed Implementation

[0029] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0030] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0031] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0032] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be obvious to those skilled in the art. This application specification and embodiments are merely exemplary.

[0033] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0034] Unless otherwise specified, "room temperature" and "normal temperature" in this invention refer to 25±2℃.

[0035] Unless otherwise specified, all raw materials or instruments used in the following embodiments of the present invention are commercially available.

[0036] Example 1

[0037] raw material:

[0038] Components Chemical name / type Mass (g) mass percentage (wt%) base oil Linear perfluoropolyether oil, molecular weight 3500 84 84.00% Thickener Polytetrafluoroethylene micro powder, with an average particle size of 2μm 13 13.00% anti-radiation agent Phenylacetyl-α-naphthylamine 0.5 0.50% pyrene 0.5 0.50% Extreme pressure anti-wear agent <![CDATA[WS2 nanosheets modified with perfluoropolyether silane (diameter 100 - 300 nm)]]> 2 2.00% Corrosion inhibitor Barium perfluorooctyl sulfonate 0.2 0.20%

[0039] Preparation method:

[0040] Pretreatment: Place 13.0g of PTFE micro powder in an oven at 105℃ and dry for 2 hours.

[0041] Premixing: In a planetary mixer, add 50.4g (60% of the total base oil) of perfluoropolyether oil. Slowly add the dry PTFE powder at 400 rpm. After the addition is complete, increase the speed to 1000 rpm and mix for 30 minutes to form a uniform paste.

[0042] Hot refining and homogenization: Start heating to raise the material to 100°C. Then turn on the high-speed shear head and shear at 6000 rpm for 75 minutes. During this process, add the remaining 33.6g of base oil in three batches.

[0043] Dispersing additives: Stop heating and cool the material to 60°C. Reduce the rotation speed to 1500 rpm and add phenyl-α-naphthylamine, pyrene, and barium perfluorooctyl sulfonate in sequence, dispersing for 15 minutes after each additive is added.

[0044] Dispersing nanoparticles: 2.0g of nano WS2 and 5.0g of reserved base oil (pre-weighed from the total oil volume) were premixed into a slurry in a beaker using a glass rod, and then slowly added to the mixing vessel at 1000rpm. After the addition was complete, the speed was increased to 2000rpm, and dispersion was continued for 60 minutes.

[0045] Vacuum degassing: Turn off the stirring and heating, turn on the vacuum pump, and reduce the pressure inside the vessel to -0.098 MPa. Degas for 40 minutes with slow stirring at 200 rpm.

[0046] Discharge and curing: Break the vacuum, discharge the prepared grease, put it into a sample container, seal it and cure it at room temperature for 24 hours before performance testing.

[0047] Example 2

[0048] The only difference between this embodiment and Example 1 is that the amount of phenyl-α-naphthylamine is 0.25g and the amount of pyrene is 0.75g.

[0049] Comparative Example 1

[0050] The only difference between this comparative example and Example 1 is that phenyl-α-naphthylamine and pyrene are not added.

[0051] Comparative Example 2

[0052] The only difference between this comparative example and Example 1 is that unmodified nano-molybdenum disulfide was used.

[0053] Experimental Example 1

[0054] The greases prepared in the above examples and comparative examples were subjected to key performance tests, and the results are shown in Table 1.

[0055] Table 1 Comparison of Performance Test Results

[0056] Test Project Example 1 Example 2 Comparative Example 1 Comparative Example 2 Working cone penetration (0.1mm) 295 288 290 310 Dropping point (°C) >320 >320 >320 >320 Evaporation loss (200℃, 22h, %) 0.85 0.89 0.82 1.25 Oil separation of steel mesh (100℃, 24h, %) 2.5 2.7 2.4 4.8 Low-temperature starting torque (-80℃, g·cm) 780 810 760 950 Four-ball wear scar diameter (392 N, mm) 0.48 0.49 0.51 0.62 Sintering load (Pd, N) 6180 6050 5880 4900 High-temperature bearing life (200℃, h) 1650 1580 1450 920 Pre-irradiation cone penetration (0.1 mm) 295 288 290 310 Cone penetration after irradiation (0.1 mm) 260 255 185 (Currently cured) 245 Rate of change of cone penetration (After 500 kGy, %) -11.90% -11.50% -36.20% -21.00%

[0057] Results Analysis and Conclusions

[0058] Radiation resistance performance analysis:

[0059] After being subjected to intense irradiation of 500 kGy, Examples 1 and 2 showed a decrease in cone penetration of only about 12%, and the liposomes remained soft and had good lubricity.

[0060] After irradiation, the cone penetration of Comparative Example 1 (without anti-radiation agent) decreased sharply by 36%, and the lipid body became significantly harder and more brittle. In practical applications, this could very likely cause the mechanism to jam, which fully demonstrates the importance of introducing a phenyl-α-naphthylamine / pyrene composite anti-radiation agent.

[0061] Comparative Example 2 (using ordinary MoS2) has better radiation resistance than Comparative Example 1 but is far worse than the present invention. This is because MoS2 itself is less stable than WS2 under radiation, and the unmodified particles are prone to agglomeration, which cannot provide stable protection.

[0062] Analysis of wide temperature range and long-term lubrication performance:

[0063] All samples exhibited excellent high-temperature resistance (dropping point > 320℃).

[0064] Examples 1 and 2 exhibit extremely low evaporation loss and excellent low-temperature start-up torque, meeting the core requirements for wide-temperature-range applications.

[0065] In terms of tribological properties, Examples 1 and 2 exhibited the smallest wear scar diameter and the highest sintering load, indicating optimal anti-wear and extreme pressure performance. This is attributed to the stable dispersion and efficient lubrication of the surface-modified WS2 nanosheets in the base oil.

[0066] Comparative Example 2, due to the use of unmodified micron-sized MoS2, exhibited a significantly higher oil separation rate (due to poor colloidal stability), increased evaporation loss (possibly due to poor compatibility leading to easier precipitation of the base oil), and significantly inferior tribological properties. This demonstrates the crucial role of nano-WS2 with specific surface modifications in maintaining the overall stability of lubricating grease performance.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A space-grade wide temperature range radiation resistant grease, characterized in that, Comprising the following components by weight: Perfluoropolyether base oil 80-85 parts Polytetrafluoroethylene thickening agent 12-16 parts Anti-radiation additive 0.8-1.5 parts Nanometer extreme pressure anti-wear agent 1.5-2.5 parts Anti-corrosion agent 0.2-0.5 parts.

2. The aerospace-grade, wide-temperature-range, radiation-resistant grease of claim 1, wherein, The perfluoropolyether base oil is a linear structure with a molecular weight of 3000 to 4000.

3. The space-grade, wide temperature range, radiation resistant grease of claim 1, wherein, The polytetrafluoroethylene thickening agent is a PTFE micro powder with an average particle size of 1~5μm.

4. The space-grade, wide temperature range, radiation resistant grease of claim 1, wherein, The anti-radiation additive is a complex of phenyl-α-naphthylamine and polycyclic aromatic compounds, compounded by phenyl-α-naphthylamine and pyrene in a mass ratio of (1:0.5) to (1:2).

5. The space-grade, wide temperature range, radiation resistant grease of claim 1, wherein, The nanometer extreme pressure anti-wear agent is tungsten disulfide nanosheet surface modified by perfluoropolyether silane coupling agent.

6. The aerospace-grade, wide-temperature-range, radiation-resistant grease of claim 1, wherein, The anti-corrosion agent is barium perfluorooctyl sulfonate.

7. A process for the preparation of a space-grade wide temperature range radiation- resistant grease according to any one of claims 1 to 6, characterized in that, Comprising the following steps: S1. Under stirring conditions, mix 50-70% perfluoropolyether base oil with polytetrafluoroethylene thickening agent to form a paste; S2. Heat and high-speed shear the paste while adding the remaining perfluoropolyether base oil, lasting for 60~90 minutes; S3. Cool the material and add the anti-radiation additive, anti-corrosion agent and nanometer extreme pressure anti-wear agent, continue to stir and disperse until uniform, and then perform degassing treatment.

8. The space-grade wide temperature range radiation resistant grease of claim 7, wherein, The heating temperature of S2 is 95~105℃.

9. The space-grade wide temperature range radiation resistant grease of claim 7, wherein, The high-speed shearing is at a shearing rate of 5000~7000rpm.

10. The space-grade, wide temperature range, radiation resistant grease of claim 7, wherein, Cool the material to 55~65℃.