Composite lubricating grease for ceramic valve element and preparation method of composite lubricating grease

Abstract

The invention discloses composite lubricating grease for a ceramic valve element and a preparation method, and relates to the technical field of lubricating grease, and the composite lubricating grease comprises the following components by mass: 60%-90% of base oil, 1%-10% of a thickening agent, 5%-25% of polytetrafluoroethylene micro powder, and 0.5%-5% of layered zirconium phosphate. Layered zirconium phosphate and polytetrafluoroethylene micro powder are compounded to prepare the ceramic valve element lubricating grease, so that the overall wear resistance and wear resistance of the lubricating grease are improved, and the prepared finished product lubricating grease has a wide use temperature range, good waterproof sealing performance and stable shear stability, and also has the advantages of high temperature resistance, high temperature resistance and the like. The wear resistance of the lubricating grease is superior to that of the ceramic valve element lubricating grease only using the polytetrafluoroethylene micro-powder solid lubricant, the wear of a ceramic material can be effectively relieved, and the service life of the ceramic valve element is prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of lubricating grease, in particular to a composite lubricating grease for a ceramic valve core and a preparation method thereof. Background Art

[0002] Ceramic valve core grease is a special grease designed for the core of water valve mechanical components - ceramic valve core, which aims to reduce the adhesive wear and abrasive wear of engineering ceramic materials under heavy load working conditions. Among them, adhesive wear is caused by the strong bond formed between relatively smooth and clean ceramic surfaces; while abrasive wear is caused by the microscopic unevenness of the ceramic surface. Therefore, ceramic valve core grease needs to have better friction reduction performance.

[0003] Traditionally, such greases are mainly composed of base oils (such as silicone oils), thickeners (such as inorganic or metal soap-based thickeners), and solid lubricants (usually polytetrafluoroethylene [PTFE] powder). Although PTFE can effectively improve the extreme pressure performance of greases, it does not significantly enhance the friction reduction and anti-wear capabilities when used alone. By combining PTFE with inorganic solid lubricants with a layered structure, these key properties can be greatly improved.

[0004] However, there are challenges in selecting suitable inorganic solid lubricants: Molybdenum disulfide: Although it has good lubricity, its resources are scarce, the cost is high and it is easily oxidized by moisture; Graphite: Although it has good lubrication effect, especially suitable for water vapor environment, its dark color affects user experience; Hydrotalcite: It helps to improve tribological properties, but its effectiveness in increasing load-bearing capacity is limited; Natural hydroxy magnesium silicate: It may pose health risks due to its needle-like fiber morphology; Layered sodium silicate: It is sensitive to moisture and may cause damage to the crystal structure, thereby reducing long-term stability.

[0005] In view of this, layered zirconium phosphate (i.e., α-zirconium phosphate), as a white powder material, shows unique advantages. It is not only chemically stable and not easily soluble in water or organic solvents, but also has a large specific surface area and surface charge density, and can form a protective film on the contact surface, significantly optimizing the load-bearing capacity and wear resistance of the grease.

[0006] More importantly, according to Announcement No. 2 of 2022 of the National Food Safety Risk Assessment Center, layered zirconium phosphate has been approved as one of the new varieties of food contact material additives, indicating that its safety has been recognized.

[0007] In summary, it is particularly important to develop a new composite ceramic valve core grease that can maintain a stable structure in a wet environment, meet user expectations for appearance characteristics, and comply with food safety standards. This will involve technical innovations that combine layered zirconium phosphate with PTFE micropowder. Summary of the invention

[0008] In view of the problems existing in the above prior art, the present invention provides a composition and preparation method of a composite ceramic valve core grease of layered zirconium phosphate and polytetrafluoroethylene micropowder. The finished grease prepared by using a specific composite combination of layered zirconium phosphate and polytetrafluoroethylene micropowder has a wide operating temperature range, good waterproof sealing and stable shear stability, and also has better anti-wear performance than ceramic valve core grease using only polytetrafluoroethylene micropowder solid lubricant, which can effectively alleviate the wear of ceramic materials and extend the service life of ceramic valve cores.

[0009] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0010] In the first aspect, the present invention provides a composite lubricating grease for a ceramic valve core, which contains the following components by mass fraction:

[0011] Base oil 60%-90%, thickener 1%-10%, polytetrafluoroethylene powder 5%-25%, layered zirconium phosphate 0.5%-5%.

[0012] Furthermore, the base oil is one or any mixture of dimethyl silicone oil, ethyl silicone oil, methylphenyl silicone oil, chlorophenyl silicone oil, methyl hydrogen silicone oil, and perfluoroalkyl silicone oil, and the kinematic viscosity ranges from 500mm2 / s to 5000mm2 / s.

[0013] Furthermore, the thickener is one or any mixture of nano silicon dioxide, nano titanium dioxide, calcium stearate soap, and calcium dodecyl stearate soap, and the specific surface area is 100-1000m2 / g.

[0014] Furthermore, the particle size D50 of the polytetrafluoroethylene powder is in the range of 2 μm-5 μm.

[0015] Furthermore, the particle size D50 of the layered zirconium phosphate is in the range of 500 nm-2 μm.

[0016] In a second aspect, the present invention further provides a method for preparing the composite grease of the ceramic valve core, comprising the following steps:

[0017] S1. Put the base oil into the reactor, turn on the stirrer, and stir the reaction at a constant speed under a certain temperature condition;

[0018] S2, stop heating, keep constant temperature, turn on the vacuum pump, and vacuum and degas while stirring;

[0019] S3. After degassing, add thickener and stir at a constant speed. After stirring, stop the constant temperature.

[0020] S4. Under certain temperature conditions, add polytetrafluoroethylene powder and layered zirconium phosphate while stirring at a constant speed;

[0021] S5. After cooling to room temperature, grind 2-4 times to obtain the finished grease.

[0022] Furthermore, in step S1, the temperature of the agitator is 120° C.-180° C., and the reaction time is 1 h-4 h.

[0023] Furthermore, in step S2, the vacuum pump is used for vacuum degassing while stirring for 0.5 h to 2 h.

[0024] Furthermore, in step S3, the uniform stirring time is 0.5h-3h.

[0025] Furthermore, in step S4, the temperature is 80°C-120°C, and the uniform stirring time is 3h-5h.

[0026] The present invention provides a composite lubricating grease for a ceramic valve core and a preparation method thereof. Compared with the prior art, the composite lubricating grease has the following beneficial effects:

[0027] By using layered zirconium phosphate and polytetrafluoroethylene micropowder to prepare ceramic valve core grease, the overall wear resistance and anti-friction performance of the grease are improved. The finished grease not only has a wide operating temperature range, good waterproof sealing and stable shear stability, but also shows superior anti-friction performance to ceramic valve core grease using only polytetrafluoroethylene micropowder solid lubricant. It can effectively alleviate the wear of ceramic materials and extend the service life of ceramic valve cores. DETAILED DESCRIPTION

[0028] The technical solutions of the present invention are described in detail below through specific embodiments. However, it should be clearly stated that these embodiments are for illustration only and are not to be construed as limiting the scope of the present invention.

[0029] Example 1

[0030] A composite lubricating grease for a ceramic valve core, comprising the following components by mass fraction:

[0031] name Quality score <![CDATA[Dimethyl silicone oil (viscosity: 1000 mm 2 / s)]]> 70％ <![CDATA[Nano-silica (specific surface area is 200 m 2 / g)]]> 5％ Polytetrafluoroethylene powder (particle size D50 = 3 μm) 24％ Layered zirconium phosphate (particle size D50 = 1 μm) 1％

[0032] The preparation method of the composite grease for the ceramic valve core comprises the following steps:

[0033] S1. Add dimethyl silicone oil into the reactor, start stirring, and stir at a constant speed at 160°C for 2 hours;

[0034] S2. Keep the temperature constant and start the vacuum pump to evacuate and degas for 1 hour;

[0035] S3, add nano-silicon dioxide, continue stirring for 1 hour and then stop heating;

[0036] S4. When the temperature drops to 90°C, add polytetrafluoroethylene powder and layered zirconium phosphate evenly while stirring, and stir for 4 hours;

[0037] S5, cooling to room temperature, grinding three times to obtain a finished product. Cooling to room temperature, grinding three times to obtain a finished product.

[0038] Example 2

[0039] A composite lubricating grease for a ceramic valve core, comprising the following components by mass fraction:

[0040] name Quality score Dimethyl silicone oil (viscosity 1000mm2 / s) 70％ Nano-silicon dioxide (specific surface area 200m2 / g) 5％ Polytetrafluoroethylene powder (particle size D50 = 3 μm) 22％ Layered zirconium phosphate (particle size D50 = 1 μm) 3％

[0041] The preparation method of the composite grease for the ceramic valve core comprises the following steps:

[0042] S1. Add dimethyl silicone oil into the reactor, start stirring, and stir at a constant speed at 160°C for 2 hours;

[0043] S2. Keep the temperature constant and start the vacuum pump to evacuate and degas for 1 hour;

[0044] S3, add nano-silicon dioxide, continue stirring for 1 hour and then stop heating;

[0045] S4. When the temperature drops to 90°C, add polytetrafluoroethylene powder and layered zirconium phosphate evenly while stirring, and stir for 4 hours;

[0046] S5, cooling to room temperature, grinding three times to obtain a finished product. Cooling to room temperature, grinding three times to obtain a finished product.

[0047] Example 3

[0048] A composite lubricating grease for a ceramic valve core, comprising the following components by mass fraction:

[0049] name Quality score Dimethyl silicone oil (viscosity 1000mm2 / s) 70％ Nano-silicon dioxide (specific surface area 200m2 / g) 5％ Polytetrafluoroethylene powder (particle size D50 = 3 μm) 20％ Layered zirconium phosphate (particle size D50 = 1 μm) 5％

[0050] The preparation method of the composite grease for the ceramic valve core comprises the following steps:

[0051] S1. Add dimethyl silicone oil into the reactor, start stirring, and stir at a constant speed at 160°C for 2 hours;

[0052] S2. Keep the temperature constant and start the vacuum pump to evacuate and degas for 1 hour;

[0053] S3, add nano-silicon dioxide, continue stirring for 1 hour and then stop heating;

[0054] S4. When the temperature drops to 90°C, add polytetrafluoroethylene powder and layered zirconium phosphate evenly while stirring, and stir for 4 hours;

[0055] S5, cooling to room temperature, grinding three times to obtain a finished product. Cooling to room temperature, grinding three times to obtain a finished product.

[0056] Comparative Example

[0057] Compared with the embodiment, the difference is that only polytetrafluoroethylene powder is used as a solid lubricant, and layered zirconium phosphate is not added for compounding, as follows:

[0058] Its composition is as follows:

[0059] name Quality score Dimethyl silicone oil (viscosity 1000mm2 / s) 70％ Nano-silicon dioxide (specific surface area 200m2 / g) 5％ Polytetrafluoroethylene powder (particle size D50 = 3 μm) 25％

[0060] The preparation method of the above comparative example comprises the following steps:

[0061] S1. Add dimethyl silicone oil into the reactor, start stirring, and stir at a constant speed at 160°C for 2 hours;

[0062] S2. Keep the temperature constant and start the vacuum pump to evacuate and degas for 1 hour;

[0063] S3, add nano-silicon dioxide, continue stirring for 1 hour and then stop heating;

[0064] S4. When the temperature drops to 90°C, add polytetrafluoroethylene powder evenly while stirring and stir for 4 hours;

[0065] S5, cooling to room temperature, grinding three times to obtain a finished product. Cooling to room temperature, grinding three times to obtain a finished product.

[0066] Test example

[0067] The performance indicators of the finished greases obtained in Examples 1-3 of the present invention and the comparative examples were measured according to the corresponding test standards. The test results are shown in Table 1.

[0068] Table 1

[0069]

[0070]

[0071] [1]: After adding lubricating medium, the ceramic valve core material is rubbed 100,000 times in a cycle, and the wear rate is calculated by measuring the mass change before and after weighing.

[0072] Through the test examples, it can be found that by determining the composition of the base oil and the thickener, and comparing the different ratios of layered zirconium phosphate and polytetrafluoroethylene powder, the basic parameters (cone penetration, copper sheet corrosion, evaporation loss, dropping point, steel mesh oil separation) of Examples 1-3 are basically the same as those of the comparative example, but there is a large gap in anti-wear performance and material wear rate. The finished grease prepared by the formula of layered zirconium phosphate and polytetrafluoroethylene powder is better than the finished grease prepared by polytetrafluoroethylene powder alone in anti-wear performance and material wear rate. This shows that by compounding and mixing layered zirconium phosphate and polytetrafluoroethylene powder, the anti-wear performance of the obtained grease can be effectively improved, and the service life of the related lubricating parts (ceramic valve core) can be extended.

[0073] In summary, the composition and preparation method of the layered zirconium phosphate and polytetrafluoroethylene micropowder composite ceramic valve core grease provided by the present invention improve the anti-wear performance of the traditional ceramic valve core grease that only uses polytetrafluoroethylene as a solid lubricant, reduce the wear of related components (ceramic valve core) caused by long-term work, and extend the service life of the ceramic valve core.

Claims

1. A composite grease for a ceramic valve core, characterized in that: Contains the following components by mass fraction: Base oil 60%-90%, thickener 1%-10%, polytetrafluoroethylene powder 5%-25%, layered zirconium phosphate 0.5%-5%.

2. The composite grease for a ceramic valve core according to claim 1, characterized in that: The base oil is one or any mixture of dimethyl silicone oil, ethyl silicone oil, methyl phenyl silicone oil, chlorophenyl silicone oil, methyl hydrogen silicone oil, and perfluoroalkyl silicone oil, and the kinematic viscosity ranges from 500mm2 / s to 5000mm2 / s.

3. The composite grease for ceramic valve core according to claim 1, characterized in that: The thickener is one or any mixture of nano silicon dioxide, nano titanium dioxide, calcium stearate soap, and calcium dodecyl stearate soap, and has a specific surface area of ​​100-1000m2 / g.

4. The composite grease for a ceramic valve core according to claim 1, characterized in that: The particle size D50 of the polytetrafluoroethylene powder is in the range of 2 μm-5 μm.

5. The composite grease for ceramic valve core according to claim 1, characterized in that: The particle size D50 of the layered zirconium phosphate is in the range of 500 nm-2 μm.

6. A composite grease for a ceramic valve core according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: S1. Put the base oil into the reactor, turn on the stirrer, and stir the reaction at a constant speed under a certain temperature condition; S2, stop heating, keep constant temperature, turn on the vacuum pump, and vacuum and degas while stirring; S3. After degassing, add thickener and stir at a constant speed. After stirring, stop the constant temperature. S4. Under certain temperature conditions, add polytetrafluoroethylene powder and layered zirconium phosphate while stirring at a constant speed; S5. After cooling to room temperature, grind 2-4 times to obtain the finished grease.

7. The method for preparing a composite grease for a ceramic valve core according to claim 6, characterized in that: In the step S1, the temperature of the stirrer is 120° C.-180° C., and the reaction time is 1 h-4 h.

8. The composite grease for ceramic valve core and preparation method according to claim 6, characterized in that: In step S2, the vacuum pump is used for vacuum degassing while stirring for 0.5 h to 2 h.

9. The composite grease for ceramic valve core and preparation method according to claim 6, characterized in that: In step S3, the uniform stirring time is 0.5h-3h.

10. The composite grease for ceramic valve core and preparation method according to claim 6, characterized in that: In step S4, the temperature is 80° C.-120° C., and the uniform stirring time is 3 h-5 h.

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