Microemulsion type cutting fluid for aerospace superhard steel and preparation method thereof

Abstract

The present application relates to the technical field of lubricant, in particular to a microemulsion cutting fluid for aerospace superhard steel and a preparation method thereof, the microemulsion cutting fluid for aerospace superhard steel comprises the following components with the weight percentage: 20-60% of deionized water, 5-40% of synthetic ester base oil, 10-70% of emulsifier, 2-10% of antirust agent, 0.1-0.8% of defoaming agent and 5-30% of extreme pressure lubricant; the preparation method comprises the following steps: adding deionized water, synthetic ester base oil, emulsifier, antirust agent, defoaming agent and extreme pressure lubricant into a container according to the set proportion, fully mixing them through ultrasonic, and standing after mixing to obtain the microemulsion cutting fluid. The microemulsion cutting fluid has excellent environmental protection performance, outstanding lubricating and extreme pressure performance, stable system, wide applicability, simple preparation process and wide application prospect in the fields of metal processing, mechanical lubrication, precision manufacturing and surface engineering.

Description

Technical Field

[0001] This invention relates to the field of lubricant technology, specifically to a microemulsion cutting fluid for aerospace superhard steel and its preparation method. Background Technology

[0002] In the aerospace equipment manufacturing field, ultra-high-strength steels such as 300M steel and A100 are widely used as key structural materials. These materials, after heat treatment, can achieve a hardness of over 50 HRC, possessing both excellent specific strength and fatigue resistance. However, their machinability is extremely prominent—high cutting forces and temperatures occur during cutting, and work hardening is severe, placing stringent requirements on the extreme pressure lubrication, cooling, and penetration properties of cutting fluids. Simultaneously, to meet the diverse machining needs of precision parts, an ideal cutting fluid must also possess good general machining performance, compatible with milling, turning, drilling, and tapping processes on various commonly used metals such as C45 carbon structural steel and 316 austenitic stainless steel.

[0003] Currently, traditional industrial lubricants mostly use mineral oil-based systems or extreme pressure additives containing chlorine or sulfur. While these can meet lubrication requirements under certain operating conditions, their high pollution and slow degradation characteristics contradict the increasingly urgent green and sustainable development needs of the aerospace industry. Against this backdrop, environmentally friendly microemulsions, with their low volatile organic compound emissions due to their water-based continuous phase, excellent biodegradability, and superior cooling performance, have gained widespread attention in aerospace equipment lubrication and precision machining scenarios, and are widely recognized as one of the ideal alternatives to traditional oil-based lubricants. Compared to traditional lubricants, environmentally friendly microemulsions not only significantly reduce the environmental impact during production and use, but their unique colloidal dispersion structure also enables precise release of lubricating components, combining cooling, lubrication, and cleaning functions. They demonstrate outstanding application potential in scenarios such as aero-engine blade machining and landing gear component molding.

[0004] However, existing environmentally friendly microemulsions generally suffer from the technical bottleneck of "difficulty in achieving a balance between environmental performance and lubrication performance." Specifically, most existing products, in pursuit of environmental indicators, adopt a single water-based system or a formulation design with low content of lubricating active components, resulting in insufficient oil film strength. When facing the high loads, high speeds, and instantaneous high-temperature impacts during the machining of high-strength materials such as aerospace-grade ultra-hard steel, existing microemulsions struggle to form a stable and continuous boundary lubrication film on the friction pair surface. The oil film is prone to rupture or being washed away by the chip flow, failing to effectively isolate the newly formed metal surface, thereby leading to problems such as accelerated tool wear, deterioration of machined surface quality, and out-of-tolerance dimensional accuracy.

[0005] Therefore, developing a microemulsion that combines extreme environmental friendliness with excellent lubrication performance, and is particularly suitable for machining ultra-hard steel for aerospace applications, is of vital importance for promoting the green transformation of high-end equipment manufacturing industries such as aerospace and improving the processing quality and yield of core components. Summary of the Invention

[0006] To address the shortcomings of existing environmentally friendly microemulsions in achieving both environmental friendliness and the high lubricity required for machining ultra-hard steel, this invention provides a microemulsion cutting fluid for aerospace ultra-hard steel and its preparation method. The primary objective of this invention is to provide a microemulsion cutting fluid that combines excellent lubrication performance with high-efficiency environmental protection. This cutting fluid uses synthetic ester lubricants as its base oil, and through rational compounding and optimization of the mass percentages of emulsifiers, rust inhibitors, defoamers, extreme pressure agents, and other components, the overall performance of the resulting cutting fluid is significantly improved, meeting the stringent machining requirements of aerospace ultra-hard steel.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows: A microemulsion cutting fluid for aerospace superhard steel comprises the following components by weight percentage: 20-60% deionized water, 5-40% synthetic ester base oil, 10-70% emulsifier, 2-10% rust inhibitor, 0.1-0.8% defoamer, and 5%-30% extreme pressure lubricant.

[0008] Preferably, the synthetic ester base oil is one or more of trimethylolpropane coconut oil ester, isooctyl oleate, polyethylene glycol fatty acid ester, and dipentaerythritol oleate.

[0009] Preferably, the emulsifier is one or more of sorbitan oleate, polyoxyethylene polyoxypropylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

[0010] Preferably, the extreme pressure lubricant is one or more of a water-soluble nonionic amide, stearic acid diethanolamide borate, and a water-soluble nonionic fatty acid amide.

[0011] Preferably, the rust inhibitor is one or more of the following: polycarboxylic acid ammonium salt, organic carboxylic acid salt, borate ester, phosphate ester, and organic amine.

[0012] Preferably, the defoamer is one or more of the following: a silicone compound, a polyether compound, or a silicone-polyether compound.

[0013] Preferably, the mass ratio of the synthetic ester base oil to the emulsifier is 1:1 to 1:20.

[0014] A method for preparing a microemulsion cutting fluid for aerospace superhard steel includes the following steps: adding deionized water, synthetic ester base oil, emulsifier, rust inhibitor, defoamer, and extreme pressure lubricant into a container in a set ratio, mixing them thoroughly by ultrasound, and allowing the mixture to stand to obtain the microemulsion cutting fluid.

[0015] Preferably, the ultrasonic mixing time is 10-30 minutes.

[0016] Compared with existing technologies, the microemulsion cutting fluid for aerospace superhard steel and its preparation method provided by the present invention have the following beneficial effects: 1. Excellent environmental performance: Synthetic esters are selected as the base oil. Their molecular structure design determines their easy biodegradability, avoiding the environmental burden caused by mineral oil and chlorine / sulfur additives from the source, which meets the stringent requirements of the aerospace field for green management of materials throughout their entire life cycle.

[0017] 2. Outstanding lubrication and extreme pressure performance: Through the synergistic effect of synthetic esters and extreme pressure lubricants, a strong and tough composite lubricating film can be formed at the machining interface of ultra-hard steels such as 300M and A100. This effectively reduces cutting resistance and tool wear, meeting the requirements of extreme cutting conditions with high loads and high speeds.

[0018] 3. Stable system and wide applicability: By optimizing the type of emulsifier and the ratio of base oil to emulsifier (1:1~1:20), a microemulsion system with uniform particle size and thermodynamic stability is formed. This cutting fluid is not only suitable for ultra-hard steel, but also suitable for milling, turning, drilling and tapping processes of various metals such as C45 steel and 316 stainless steel.

[0019] 4. Simple preparation process, easy to promote: The preparation process only requires ultrasonic mixing at room temperature, without the need for complex heating or high pressure equipment. The process is short and easy to realize industrial production and rapid on-site preparation, with significant cost advantages and application potential.

[0020] 5. The microemulsion cutting fluid prepared by this invention has broad application prospects in metal processing, mechanical lubrication, precision manufacturing, surface engineering and other fields. Attached Figure Description

[0021] Figure 1 This is a particle size distribution diagram of the microemulsion cutting fluid prepared in Example 1 of the present invention; Figure 2 This is a graph showing the change in the friction coefficient over time of the microemulsion cutting fluid prepared in Example 1 of the present invention. Figure 3 This is a graph showing the change in the friction coefficient over time of the microemulsion cutting fluid prepared in Example 2 of the present invention. Figure 4This is a graph showing the change in the friction coefficient over time of the microemulsion cutting fluid prepared in Example 3 of the present invention. Detailed Implementation

[0022] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer as a result. However, these embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0023] This invention provides the following technical solution: A microemulsion cutting fluid for aerospace superhard steel comprises the following components by weight percentage: 20-60% deionized water, 5-40% synthetic ester base oil, 10-70% emulsifier, 2-10% rust inhibitor, 0.1-0.8% defoamer, and 5%-30% extreme pressure lubricant.

[0024] Specifically, the synthetic ester base oil is one or more of trimethylolpropane coconut oil ester, isooctyl oleate, polyethylene glycol fatty acid ester, and dipentaerythritol oleate. Using synthetic esters as base oils balances excellent lubricating activity with environmentally friendly biodegradability, ensuring the product's environmental characteristics from the source.

[0025] Specifically, the emulsifier is one or more of sorbitan oleate, polyoxyethylene polyoxypropylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene fatty acid ester, and polyoxyethylene sorbitan fatty acid ester. By selecting the optimal type of emulsifier, the compatibility between the oil phase (synthetic ester base oil) and the aqueous phase can be improved, ensuring the long-term stability of the microemulsion system.

[0026] Specifically, the extreme pressure lubricant is one or more of water-soluble nonionic amides, stearic acid diethanolamide borate ester, and water-soluble nonionic fatty acid amides. It can chemically react with the metal surface under high load conditions to form a high-strength chemical lubricating film, thereby improving the oil film's load-bearing capacity.

[0027] Specifically, the rust inhibitor is one or more of polycarboxylic acid ammonium salts, organic carboxylic acid salts, borate esters, phosphate esters, and organic amines. It can form a dense rust-preventive protective film on the metal surface, preventing equipment parts from rusting.

[0028] Specifically, the defoamer is one or more of the following: organosilicon compound, polyether compound, or organosilicon-polyether compound. It can effectively suppress foaming of the microemulsion during stirring and recycling, ensuring the stability of lubrication and cooling effects.

[0029] Specifically, the mass ratio of the synthetic ester base oil to the emulsifier is 1:1 to 1:20. This ratio range ensures sufficient emulsification and dispersion of the oil phase, forming a microemulsion system with uniform particle size and strong stability, while avoiding excessive emulsifier that could lead to decreased environmental friendliness or increased costs.

[0030] A method for preparing a microemulsion cutting fluid for aerospace superhard steel includes the following steps: adding deionized water, synthetic ester base oil, emulsifier, rust inhibitor, defoamer, and extreme pressure lubricant into a container in a set ratio, mixing them thoroughly by ultrasound, and allowing the mixture to stand to obtain the microemulsion cutting fluid.

[0031] Specifically, the ultrasonic mixing time is 10-30 minutes.

[0032] Based on the above technical solutions, the embodiments of the present invention will be described in detail below by way of examples: Example

[0033] 5g of isooctyl oleate, 10g of polyoxyethylene polyoxypropylene ether, and 4g of stearic acid diethanolamide borate were mixed, and then 30g of deionized water was slowly added dropwise. The resulting mixed solution had a base oil to emulsifier mass ratio of 1:2. The solution was then sonicated for 30 minutes to ensure thorough mixing, thus obtaining the basic microemulsion. Figure 1 This is a particle size distribution diagram of the microemulsion.

[0034] Then, add 0.2g of defoamer and 2g of rust inhibitor to the flask and stir for 1 hour to obtain a green microemulsion.

[0035] To test the tribological properties of the prepared green liquid lubricant, a ball-and-disc friction and wear testing machine (TRB, Anton Paar) was used. The experiment employed a reciprocating friction mode, with a 6mm diameter YG8 ball as the upper friction pair and a 300mm steel block as the lower friction pair. Before the experiment, the friction pairs were immersed in ethanol and acetone solutions respectively and ultrasonically treated for 15 minutes to remove surface impurities. Then, the friction pairs were removed and dried in an oven. The experimental parameters were: load 15N, frequency 2Hz, and amplitude 2mm. Based on the test results, the curve showing the change in the coefficient of friction between the friction pairs over time is shown below. Figure 2 As shown in the figure, after a period of break-in, the coefficient of friction eventually stabilizes at around 0.121.

[0036] Example 2: 3g of trimethylolpropane coconut oil ester, 15g of dehydrated sorbitan oleate, and 4g of water-soluble amide were mixed, and then 30g of deionized water was slowly added dropwise. The resulting mixed solution had a base oil to emulsifier mass ratio of 1:5. The solution was then sonicated for 30 minutes to ensure thorough mixing, thus obtaining the basic microemulsion.

[0037] Then, add 0.2g of defoamer and 2g of rust inhibitor to the flask and stir for 1 hour to obtain a green microemulsion.

[0038] To test the tribological properties of the prepared green liquid lubricant, a ball-and-disc friction and wear testing machine (TRB, Anton Paar) was used. The experiment employed a reciprocating friction mode, with the upper friction pair consisting of YG8 balls with a diameter of 6 mm and the lower friction pair consisting of A100 steel blocks. Before the experiment, the friction pairs were immersed in ethanol and acetone solutions respectively and ultrasonically treated for 15 minutes to remove surface impurities. Then, the friction pairs were removed and dried in an oven. The experimental parameters were: load 15 N, frequency 2 Hz, and amplitude 2 mm. Based on the test results, the curve showing the change in the coefficient of friction between the friction pairs of the prepared green liquid lubricant over time is shown below. Figure 3 As shown in the figure, after a period of break-in, the coefficient of friction eventually stabilizes at around 0.124.

[0039] Example 3: 5g of polyethylene glycol fatty acid ester, 20g of alkylphenol polyoxyethylene ether, and 5g of water-soluble fatty acid amide were mixed, and then 40g of deionized water was slowly added dropwise. The resulting mixed solution had a base oil to emulsifier mass ratio of 1:4. The solution was then sonicated for 30 minutes to ensure thorough mixing, thus obtaining the basic microemulsion.

[0040] Then, add 0.2g of defoamer and 2g of rust inhibitor to the flask and stir for 1 hour to obtain a green microemulsion.

[0041] To test the tribological properties of the prepared green liquid lubricant, a ball-and-disc friction and wear testing machine (TRB, Anton Paar) was used. The experiment employed a reciprocating friction mode, with a 6mm diameter YG8 ball as the upper friction pair and a 300mm steel block as the lower friction pair. Before the experiment, the friction pairs were immersed in ethanol and acetone solutions respectively and ultrasonically treated for 15 minutes to remove surface impurities. Then, the friction pairs were removed and dried in an oven. The experimental parameters were: load 15N, frequency 2Hz, and amplitude 2mm. Based on the test results, the curve showing the change in the coefficient of friction between the friction pairs over time is shown below. Figure 4 As shown in the figure, after a period of break-in, the coefficient of friction eventually stabilizes at around 0.123.

[0042] This invention uses synthetic esters as the base oil, whose readily biodegradable properties give the product a core environmental advantage, meeting the stringent ecological control requirements of the aerospace industry regarding lubricant leakage risks. Through the rational compounding and precise optimization of functional components such as emulsifiers and rust inhibitors, the components synergistically enhance each other, enabling the cutting fluid to form a stable and extreme-condition-resistant lubricating film on the surface of ultra-hard steels such as 300M and A100, as well as cemented carbide cutting tools, significantly reducing the coefficient of friction (stabilizing at around 0.12), thereby ensuring machining accuracy and tool life. Furthermore, the simple preparation process and controllable cost make this cutting fluid suitable not only for core applications such as aero-engine blades, landing gear, and spacecraft structural components, but also for general machining fields, demonstrating broad application prospects.

Claims

1. A microemulsion cutting fluid for aerospace superhard steel, characterized in that: It includes the following components by weight percentage: 20-60% deionized water, 5-40% synthetic ester base oil, 10-70% emulsifier, 2-10% rust inhibitor, 0.1-0.8% defoamer, and 5%-30% extreme pressure lubricant.

2. The microemulsion cutting fluid for aerospace superhard steel as described in claim 1, characterized in that: The synthetic ester base oil is one or more of trimethylolpropane coconut oil ester, isooctyl oleate, polyethylene glycol fatty acid ester, and dipentaerythritol oleate.

3. The microemulsion cutting fluid for aerospace superhard steel as described in claim 1, characterized in that: The emulsifier is one or more of the following: sorbitan oleate, polyoxyethylene polyoxypropylene ether, alkylphenol polyoxyethylene ether, polyoxyethylene fatty acid ester, and polyoxyethylene sorbitan fatty acid ester.

4. The microemulsion cutting fluid for aerospace superhard steel as described in claim 1, characterized in that: The extreme pressure lubricant is one or more of the following: water-soluble nonionic amide, stearic acid diethanolamide borate ester, and water-soluble nonionic fatty acid amide.

5. The microemulsion cutting fluid for aerospace superhard steel as described in claim 1, characterized in that: The rust inhibitor is one or more of the following: polycarboxylic acid ammonium salt, organic carboxylic acid salt, borate ester, phosphate ester, and organic amine.

6. The microemulsion cutting fluid for aerospace superhard steel as described in claim 1, characterized in that: The defoamer is one or more of the following: organosilicon compound, polyether, or organosilicon-polyether compound.

7. The microemulsion cutting fluid for aerospace superhard steel as described in claim 1, characterized in that: The mass ratio of the synthetic ester base oil to the emulsifier is 1:1 to 1:

20.

8. The method for preparing a microemulsion cutting fluid for aerospace superhard steel as described in claim 1, characterized in that, The process includes the following steps: adding deionized water, synthetic ester base oil, emulsifier, rust inhibitor, defoamer, and extreme pressure lubricant into a container in a set ratio, mixing them thoroughly by ultrasound, and allowing them to stand after mixing to obtain the microemulsion cutting fluid.

9. The method for preparing a microemulsion cutting fluid for aerospace superhard steel as described in claim 8, characterized in that: The ultrasonic mixing time is 10-30 minutes.

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