A solid-liquid composite lubricating paint and coating based on Pickering emulsion and preparation method thereof

Abstract

The present invention provides a solid-liquid composite lubricating coating and coating based on Pickering emulsion and a preparation method thereof, which belongs to the technical field of lubricating coatings. The present invention is to mix a polymer resin, N,N-dimethylformamide, a liquid lubricant and a nano-assembly material to obtain a solid-liquid composite lubricating coating based on Pickering emulsion. In the present invention, the nano-assembly material can act as a reinforcing agent to play a role in the dispersion strengthening of the solid phase matrix, and at the same time spontaneously construct a Pickering emulsion with the lubricant droplets, which can effectively regulate the size, distribution and degree of freedom of the droplets. The present invention introduces the Pickering emulsion into the polymer-based solid-liquid lubricating coating, while improving the mechanical strength and oil yield, and combining the high adsorption energy of the interface friction film to the oil to construct a stable surface interface oil film, thereby obtaining a solid-liquid composite lubricating coating with high wear resistance and low friction coefficient.

Description

Technical Field

[0001] The present invention relates to the technical field of lubricating coatings, and in particular to a solid-liquid composite lubricating coating and coating based on Pickering emulsion and a preparation method thereof. Background Art

[0002] Friction and wear are widespread in many engineering fields and can lead to the failure of mechanical components. Therefore, how to rationally improve the lubrication conditions between mechanical components to minimize the coefficient of friction and reduce wear is an important issue that needs to be addressed in tribology research.

[0003] Currently, polymer lubricating materials in the form of solid coatings have been widely studied in engineering applications. Their lubrication performance is mostly achieved by adding solid lubricants such as MoS2, graphene, and PTFE to the polymer coating, with an overall friction coefficient greater than 0.04. When liquid lubricants are used instead of solid lubricants, it is expected to break through the friction coefficient threshold of existing polymer coatings. Attempts by researchers to develop solid-liquid composite lubricating coatings include encapsulating liquid lubricants in microcontainers and then compounding them with polymers, or constructing pitcher plant-inspired liquid injection surfaces. However, these efforts also face difficulties in industrial promotion, relatively high friction coefficients, and the difficulty of failure under medium, high, and low loads.

[0004] Previous research has shown that the long-term, stable, ultra-low friction state of solid-liquid composite lubricating coatings depends on the stability of the interfacial oil film. This requires, on the one hand, improving the mechanical load-bearing capacity of the substrate to maintain a stable friction interface structure; on the other hand, the liquid lubricant must have a certain degree of freedom of migration. Therefore, a stable interfacial oil film can only be achieved by increasing the oil yield while maintaining high mechanical strength.

[0005] Therefore, it is of great significance to provide a solid-liquid composite lubricating coating that can improve mechanical strength and oil yield, and then obtain a solid-liquid composite lubricating coating that breaks through the low threshold of friction coefficient. Summary of the Invention

[0006] The purpose of the present invention is to provide a solid-liquid composite lubricating coating and coating based on Pickering emulsion and a preparation method thereof, so as to solve the technical problems in the prior art of the solid-liquid composite lubricating coating, such as the difficulty in industrial promotion, the high friction coefficient and the easy failure under medium, high and low loads.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a solid-liquid composite lubricating coating based on Pickering emulsion, comprising the following raw materials in mass fractions: 65-80% of N,N-dimethylformamide, 15-30% of polymer resin, 0.5-3% of liquid lubricant and 0.5-3% of nano-assembly material.

[0009] Furthermore, the preparation method of the nano-assembly material comprises the following steps:

[0010] 1) The nanomaterial powder is subjected to ablation treatment, centrifugation and drying in sequence to obtain active nanomaterial powder;

[0011] 2) mixing the active nanomaterial powder and the modifier and drying the mixture to obtain modified nanomaterial powder;

[0012] 3) Adding the modified nanomaterial powder into a liquid lubricant, allowing the mixture to stand and dry in sequence to obtain a nanoassembly material.

[0013] Furthermore, in step 1), the ablation treatment is performed in an HCl solution, and the concentration of the HCl solution is 2-5 mol / L;

[0014] The centrifugal speed is 2500-3500 r / min, the centrifugal time is 3-7 min, the drying temperature is 50-100° C., and the drying time is 4-8 h;

[0015] The nano material powder includes attapulgite powder, nano hollow SiO2, nano serpentine, starch or nano metal particles.

[0016] Furthermore, in step 2), the modifier includes hexadecyltrimethylammonium bromide, and the mass ratio of the nanomaterial powder to the modifier is 1:0.1~1.

[0017] Furthermore, in step 2), the mixing time is 10-15 hours and the mixing temperature is 40-75°C;

[0018] The drying time is 4-8 hours, and the drying temperature is 60-100°C.

[0019] Furthermore, in step 3), the liquid lubricant is a mineral lubricant, a synthetic lubricant or an ionic liquid;

[0020] The standing time is 2 to 6 hours, the drying temperature is 45 to 60° C., and the drying time is 10 to 15 hours.

[0021] Furthermore, the polymer resin includes polyamide-imide resin, polyimide resin and polyetheretherketone resin.

[0022] The present invention provides a method for preparing a solid-liquid composite lubricating coating based on Pickering emulsion, wherein N,N-dimethylformamide, a polymer resin, a liquid lubricant and a nano-assembly material are mixed to obtain the solid-liquid composite lubricating coating.

[0023] The present invention provides a method for preparing a coating from a solid-liquid composite lubricating coating based on a Pickering emulsion, wherein the solid-liquid composite lubricating coating based on a Pickering emulsion is sprayed onto a substrate, and the solid-liquid composite lubricating coating based on the Pickering emulsion is obtained after curing.

[0024] The coating thickness obtained by each spraying is 1~5μm, and the number of spraying times is 5~30 times;

[0025] The curing temperature is 200-270°C.

[0026] The invention provides a Pickering emulsion-based solid-liquid composite lubricating coating prepared by the method.

[0027] Beneficial effects of the present invention:

[0028] The present invention designs and synthesizes a solid-liquid composite lubricating coating based on Pickering emulsion. By designing a nano-assembly material with strong two-phase wettability based on nanomaterial powder, the assembly material can construct a Pickering emulsion with lubricant droplets in the solid-liquid composite system to effectively control the size, distribution and degree of freedom of the droplets. In addition, the modified nanomaterial can act as a reinforcing agent to enhance the dispersion of the solid phase matrix. Furthermore, the nano-assembly material can induce the formation of an interfacial solid friction film during the friction process and has a stronger oil film adsorption capacity. The present invention can simultaneously improve mechanical strength and oil yield, and combined with the high adsorption energy of the interfacial friction film for oil, it can construct a stable surface interface oil film, thereby exhibiting high wear resistance and a low friction coefficient. DETAILED DESCRIPTION

[0029] The present invention provides a solid-liquid composite lubricating coating based on Pickering emulsion, comprising the following raw materials in mass fractions: 65-80% N,N-dimethylformamide, 15-30% polymer resin, 0.5-3% liquid lubricant and 0.5-3% nano-assembly material, preferably 70-75% N,N-dimethylformamide, 20-27% polymer resin, 1-2% liquid lubricant and 1-2% nano-assembly material.

[0030] In the present invention, the method for preparing the nano-assembly material comprises the following steps:

[0031] 1) The nanomaterial powder is subjected to ablation treatment, centrifugation and drying in sequence to obtain active nanomaterial powder;

[0032] 2) mixing the active nanomaterial powder and the modifier and drying the mixture to obtain modified nanomaterial powder;

[0033] 3) adding a liquid lubricant to the modified nanomaterial powder, allowing the mixture to stand and dry in sequence to obtain a nanoassembly material.

[0034] In the present invention, in step 1), the ablation treatment is carried out in an HCl solution, and the concentration of the HCl solution is 2-5 mol / L, preferably 3 mol / L;

[0035] The centrifugal speed is 2500-3500 r / min, preferably 2700-3200 r / min, more preferably 3000 r / min, the centrifugal time is 3-7 min, preferably 5 min, the drying temperature is 50-100° C., preferably 75-90° C., more preferably 80° C., and the drying time is 4-8 h, preferably 6 h;

[0036] The nanomaterial includes attapulgite powder, nano hollow SiO2, nano serpentine, starch or nano metal particles, preferably attapulgite powder (ATP).

[0037] In the present invention, the ablation treatment is to mix the nano material powder and the HCl solution and continuously stir them for 120 hours in a sealed environment.

[0038] In the present invention, centrifugation is performed in deionized water, and after the centrifugation is completed, washing is performed and then drying is performed.

[0039] In the present invention, in step 2), the modifier is preferably cetyltrimethylammonium bromide, and the mass ratio of the nanomaterial powder to the modifier is 1:0.1-1, preferably 1:0.4.

[0040] In the present invention, in step 2), the mixing time is 10 to 15 hours, preferably 11 to 13 hours, more preferably 12 hours, and the mixing temperature is 40 to 75°C, preferably 50 to 65°C, more preferably 60°C;

[0041] The drying time is 4 to 8 hours, preferably 6 hours, and the drying temperature is 60 to 100°C, preferably 70 to 90°C, and more preferably 80°C.

[0042] In the present invention, the modified nanomaterial is an active nanomaterial grafted with a non-polar alkyl long chain.

[0043] In the present invention, in step 3), the liquid lubricant is a mineral lubricant, a synthetic lubricant or an ionic liquid, preferably a synthetic lubricant;

[0044] The standing time is 2 to 6 hours, preferably 4 hours, the drying temperature is 45 to 60° C., preferably 50° C., and the drying time is 10 to 15 hours, preferably 11 to 13 hours, and more preferably 12 hours.

[0045] In the present invention, the liquid lubricant is added to the modified nanomaterial powder by dripping the liquid lubricant from a constant pressure funnel into the modified nanomaterial powder under a pressure condition of -0.1 MPa.

[0046] In the present invention, the polymer resin is a polyamide-imide resin, a polyimide resin, and a polyetheretherketone resin, preferably a polyamide-imide resin.

[0047] The present invention provides a method for preparing a solid-liquid composite lubricating coating based on Pickering emulsion, wherein N,N-dimethylformamide, a polymer resin, a liquid lubricant and a nano-assembly material are mixed to obtain the solid-liquid composite lubricating coating.

[0048] In the present invention, the polymer resin and the liquid lubricant are first mixed, and then N,N-dimethylformamide is added and the solid content of the system is adjusted to 20-30%.

[0049] The present invention provides a method for preparing a coating from a solid-liquid composite lubricating coating based on a Pickering emulsion, wherein the solid-liquid composite lubricating coating based on a Pickering emulsion is sprayed onto a substrate, and the solid-liquid composite lubricating coating based on the Pickering emulsion is obtained after curing.

[0050] The coating thickness obtained by each spraying is 1-5 μm, preferably 2-3 μm, and the number of spraying is 5-30 times, preferably 10 times;

[0051] The curing temperature is 200-270°C, preferably 220°C.

[0052] In the present invention, the solid-liquid composite lubricating coating is sprayed after being emulsified and dispersed through high-speed shearing.

[0053] The invention provides a Pickering emulsion-based solid-liquid composite lubricating coating prepared by the method.

[0054] 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.

[0055] In the examples, attapulgite (ATP) was purchased from Mingguang, Anhui Province, hexadecyltrimethylammonium bromide was purchased from Sinopharm Shanghai Chemical Reagent Co., Ltd., N, N-dimethylformamide was purchased from Tianjin Longbohua Pharmaceutical Chemistry Co., Ltd., methyl silicone oil was provided by Hangzhou Sili Silicone Factory, polyamide-imide resin was provided by Beijing Huatong Ruichi Material Technology Co., Ltd., and concentrated hydrochloric acid and petroleum ether were purchased from Li'an Longbohua Pharmaceutical Chemistry Co., Ltd. Example 1

[0056] 25 mL of concentrated hydrochloric acid (12 mol / L) was added to 100 g of deionized water, and 5 g of attapulgite powder (ATP) was added to the acid solution. The mixture was stirred continuously for 120 h in a sealed environment and centrifuged at 3000 r / min in deionized water for 5 min. After centrifugation, it was washed three times with deionized water and dried at 80°C for 6 h to obtain the active nanomaterial C-ATP. 3 g of C-ATP and 1.2 g of hexadecyltrimethylammonium bromide were mixed in deionized water (80 g), stirred at 60°C for 12 h, filtered, and dried at 80°C for 6 h to obtain the modified nanomaterial powder F-ATP. The prepared F-ATP powder was placed in a room temperature conical flask, and methyl silicone oil diluted with toluene (toluene:silicone oil mass ratio of 1:1) was added to a constant pressure funnel. The entire device was allowed to stand under vacuum for 20 min, and then the piston of the constant pressure funnel was rotated to allow the methyl silicone oil to drip into the F-ATP and mix. The mixture was kept under vacuum for 4 h, then washed with petroleum ether to remove the residual methyl silicone oil on the surface, and dried at 50°C for 12 h to obtain the nano-assembled material MF-ATP.

[0057] 0.25 g of methyl silicone oil, 15 g of N,N-dimethylformamide, and 0.25 g of MF-ATP were added to 5 g of polyamide-imide resin. The methyl silicone oil droplets were then pulverized by high-speed shear emulsification dispersion (4000 r / min for 5 min) to produce a Pickering emulsion-based solid-liquid composite lubricating coating. This coating was then sprayed onto a sandblasted stainless steel substrate 13 times, with each spraying producing a coating thickness of 2 μm. The coating was then cured at 220°C. This resulted in a Pickering emulsion-based polyamide-imide-based solid-liquid composite lubricating coating.

[0058] The nanoassembled material MF-ATP prepared in this example exhibited a water contact angle of 82°, very close to 90°, indicating extremely strong biphasic wettability. The resulting Pickering emulsion-based polyamide-imide-based solid-liquid composite lubricating coating exhibited a microhardness greater than 173.21 MPa. In a ball-on-disc friction test at 5 N and 7.5 Hz, the resulting coating exhibited a low coefficient of friction of 0.042 and a long lifespan of 1500 m (dual: 6 mm diameter GCr15 steel ball; reciprocating diameter: 5 mm), demonstrating superior friction and wear reduction performance to existing polyamide-imide-based lubricating coatings. Example 2

[0059] Different from Example 1, the solid-liquid composite lubricating coating based on Pickering emulsion is composed of the following raw material components: 5g polyamide-imide resin, 0.3g nano-assembly material MF-ATP, 15g N,N-dimethylformamide and 0.25g methyl silicone oil. The number of spraying times is 10 times, and the coating thickness produced by each spraying cycle is 3μm.

[0060] The nanoassembled material MF-ATP prepared in this example exhibited a water contact angle of 82°, very close to 90°, indicating extremely strong biphasic wettability. The resulting Pickering emulsion-based polyamide-imide-based solid-liquid composite lubricating coating exhibited a microhardness greater than 177.21 MPa. The resulting coating exhibited a low coefficient of friction of 0.036 in a 5 N, 7.5 Hz ball-on-disc friction test and a long lifespan of 1700 m (dual: 6 mm diameter GCr15 steel ball; reciprocating diameter: 5 mm), demonstrating superior friction and wear reduction performance to existing polyamide-imide-based lubricating coatings. Example 3

[0061] Different from Example 1, the solid-liquid composite lubricating coating based on Pickering emulsion is composed of the following raw material components: 15g polyamide-imide resin, 0.5g nano-assembly material MF-ATP, 65g N,N-dimethylformamide and 0.5g methyl silicone oil. The number of spraying times is 8 times, and the coating thickness produced by each spraying cycle is 3μm.

[0062] The nanoassembled material MF-ATP prepared in this example exhibited a water contact angle of up to 80°, very close to 90°, indicating extremely strong biphasic wettability. The resulting Pickering emulsion-based polyamide-imide-based solid-liquid composite lubricating coating exhibited a microhardness greater than 123.5 MPa. The resulting coating exhibited a low coefficient of friction of 0.038 in a 5 N, 7.5 Hz ball-on-disc friction test and a long lifespan of 1600 m (dual: 6 mm diameter GCr15 steel ball; reciprocating diameter: 5 mm), demonstrating superior friction and wear reduction performance to existing polyamide-imide-based lubricating coatings. Example 4

[0063] Different from Example 1, the solid-liquid composite lubricating coating based on Pickering emulsion is composed of the following raw material components: 20g polyamide-imide resin, 1g nano-assembly material MF-ATP, 75g N,N-dimethylformamide and 1.2g methyl silicone oil. The number of spraying times is 9 times, and the coating thickness produced by each spraying cycle is 3μm.

[0064] The nanoassembled material MF-ATP prepared in this example exhibited a water contact angle of up to 80°, very close to 90°, indicating extremely strong biphasic wettability. The resulting Pickering emulsion-based polyamide-imide-based solid-liquid composite lubricating coating exhibited a microhardness greater than 122.5 MPa. The resulting coating exhibited a low coefficient of friction of 0.040 in a 5 N, 7.5 Hz ball-on-disc friction test and a long lifespan of 1400 m (dual: 6 mm diameter GCr15 steel ball; reciprocating diameter: 5 mm), demonstrating superior friction and wear reduction performance to existing polyamide-imide-based lubricating coatings. Comparative Example 1

[0065] Unlike Example 1, the Pickering emulsion-based solid-liquid composite lubricating coating does not include the steps of adding the modified nanomaterial powder F-ATP to the liquid lubricant, allowing it to stand, and then drying it to obtain the nanoassembly material MF-ATP. The resulting Pickering emulsion-based polyamide-imide-based solid-liquid composite lubricating coating is a result.

[0066] The water contact angle of the F-ATP prepared in this comparative example was 44.9°, somewhat below 90° but significantly higher than that of the original ATP (17.2°), demonstrating significantly improved lipophilicity. The resulting Pickering emulsion-based polyamide-imide-based solid-liquid composite lubricating coating exhibited a microhardness exceeding 104.63 MPa. The resulting coating exhibited a low coefficient of friction of 0.048 in a ball-on-disc friction test at 5 N and 7.5 Hz, and a lifespan of 800 m (dual: 6 mm diameter GCr15 steel ball; reciprocating diameter: 5 mm). Comparative Example 2

[0067] Different from Example 1, the solid-liquid composite lubricating coating is composed of the following raw material components: 5g polyamide-imide resin, 15g N,N-dimethylformamide and 0.25g methyl silicone oil, thereby obtaining a polyamide-imide-based solid-liquid composite lubricating coating.

[0068] The polyamide-imide-based solid-liquid composite lubricating coating prepared in this comparative example exhibited a friction coefficient of 0.054 and a friction life of 500 m in a ball-on-disc friction test at 5 N and 7.5 Hz (counterpart: GCr15 steel ball with a diameter of 6 mm; reciprocating diameter: 5 mm). Comparative Example 3

[0069] Different from Example 1, the solid-liquid composite lubricating coating is composed of 5 g of polyamide-imide resin and 15 g of N,N-dimethylformamide, thereby obtaining a polyamide-imide-based lubricating coating.

[0070] The coating prepared in this comparative example exhibited a friction coefficient of 0.24 and a friction life of 240 m in a ball-on-disc friction test at 5 N and 7.5 Hz (couple: GCr15 steel ball with a diameter of 6 mm; reciprocating diameter: 5 mm).

[0071] As can be seen from the above examples, the present invention provides a solid-liquid composite lubricating coating and paint based on a Pickering emulsion. The Pickering emulsion in the coating can simultaneously improve mechanical strength and oil yield. Combined with the high oil adsorption capacity of the interfacial friction film, it can form a stable interfacial oil film, resulting in high wear resistance and a low coefficient of friction, effectively enhancing the mechanical strength of the solid-phase matrix.

[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 solid-liquid composite lubricating coating based on Pickering emulsion, characterized in that: The method comprises the following raw materials by mass fraction: 65-80% of N,N-dimethylformamide, 15-30% of polymer resin, 0.5-3% of liquid lubricant and 0.5-3% of nano-assembly material; The preparation method of the nano-assembly material comprises the following steps: 1) performing ablation treatment, centrifugation and drying on the nanomaterial powder in sequence to obtain active nanomaterial powder; 2) mixing the active nanomaterial powder and the modifier and drying the mixture to obtain a modified nanomaterial powder; 3) adding a liquid lubricant to the modified nanomaterial powder, allowing the mixture to stand and dry to obtain a nanoassembly material; In step 1), the nanomaterial powder is attapulgite powder; In step 2), the modifier is hexadecyltrimethylammonium bromide, and the mass ratio of the nanomaterial powder to the modifier is 1:0.1-1.

2. The solid-liquid composite lubricating coating based on Pickering emulsion according to claim 1, characterized in that: In step 1), the ablation treatment is carried out in an HCl solution having a concentration of 2 to 5 mol / L; The centrifugal speed is 2500-3500 r / min, the centrifugal time is 3-7 minutes, the drying temperature is 50-100° C., and the drying time is 4-8 hours.

3. A solid-liquid composite lubricating coating based on Pickering emulsion according to claim 1 or 2, characterized in that: In step 2), the mixing time is 10 to 15 hours and the mixing temperature is 40 to 75° C.; The drying time is 4 to 8 hours, and the drying temperature is 60 to 100°C.

4. The solid-liquid composite lubricating coating based on Pickering emulsion according to claim 3, characterized in that: In step 3), the liquid lubricant is a mineral lubricant, a synthetic lubricant or an ionic liquid; The standing time is 2 to 6 hours, the drying temperature is 45 to 60° C., and the drying time is 10 to 15 hours.

5. The solid-liquid composite lubricating coating based on Pickering emulsion according to claim 4, characterized in that: The polymer resin includes polyamide-imide resin, polyimide resin or polyetheretherketone resin.

6. The method for preparing a solid-liquid composite lubricating coating based on Pickering emulsion according to any one of claims 1 to 5, characterized in that: N,N-dimethylformamide, polymer resin, liquid lubricant and nano-assembly material are mixed to obtain a solid-liquid composite lubricating coating.

7. The method for preparing a coating of a solid-liquid composite lubricating coating based on a Pickering emulsion according to claim 1, characterized in that: Spraying a Pickering emulsion-based solid-liquid composite lubricating coating onto a substrate, and curing the coating to obtain a Pickering emulsion-based solid-liquid composite lubricating coating; The coating thickness obtained by each spraying is 1 to 5 μm, and the number of spraying times is 5 to 30 times; The curing temperature is 200-270°C.

8. A solid-liquid composite lubricating coating based on Pickering emulsion prepared by the method of claim 7.