An aircraft engine internal cleaner and method of making same

Abstract

The application discloses an aircraft engine internal cleaning agent and a preparation method thereof, and comprises the following components in parts by weight: sodium dodecyl benzene sulfonate 2-5 parts, isomeric alcohol ether 2-5 parts, fatty alcohol polyoxyethylene ether 5-10 parts, chelating dispersant 2-5 parts, multi-element corrosion inhibitor 3-8 parts, organic solvent 3-8 parts, and deionized water 45-70 parts. The aircraft engine internal cleaning agent can quickly dissolve dense carbon deposition under the assistance of the organic solvent and the isomeric alcohol ether, and can form a complete decontamination chain in three dimensions of emulsification, penetration and dispersion through the synergistic cooperation of three surfactants, so that the decontamination capacity is further improved. The chelating dispersant ensures the cleaning efficiency and stability, prevents redeposition, and the multi-element corrosion inhibitor protects the metal matrix. In the case that no inorganic salt corrosion inhibitor is used, the aircraft engine internal cleaning agent with the advantages of high oil and carbon deposition removal efficiency, low corrosion and low ash content can meet the requirements of the airworthiness standard of the aircraft engine and has excellent application value.

Description

Technical Field

[0001] This invention relates to the field of engine cleaning agent technology, specifically to an internal cleaning agent for aircraft engines and its preparation method. Background Technology

[0002] Aircraft engines operate under harsh conditions of high temperature and high speed for extended periods, inevitably leading to the accumulation of various contaminants in their internal airflow components. These contaminants include carbon deposits and sintered carbonaceous deposits formed from the high-temperature oxidation and decomposition of fuel and lubricating oil, as well as dust and salt from the air. The presence of these contaminants can disrupt the shape of the engine's internal aerodynamic flow channels, reduce the efficiency of the compressor and turbine, increase fuel consumption, and in severe cases, may clog blade cooling channels, causing overheating and erosion of hot-end components, directly threatening flight safety. Therefore, regular or as-needed cleaning or protection of the engine's internal components can effectively remove deposits such as carbon, salt, dirt, and oil adhering to the intake duct and compressor blades, thereby delaying or eliminating the impact of contaminants on engine performance, restoring degraded performance, maintaining the engine's design life, and preventing or eliminating the development of certain engine malfunctions.

[0003] Currently, cleaning agents for aircraft engine interiors are mainly divided into two categories: solvent-based and water-based. Solvent-based cleaning agents use hydrocarbons, alcohol ethers, or halogenated hydrocarbons as the main active ingredients, relying on dissolution to remove oil and carbon deposits. They have the advantages of fast cleaning speed and good removal of heavy-duty dirt. However, solvent-based products generally have safety and environmental problems such as high volatile organic compound content, low flash point and flammability, and irritating odor. Some halogenated hydrocarbon solvents also have a destructive effect on the atmospheric ozone layer, and their application is subject to increasingly stringent regulations. Water-based cleaning agents use water as the main solvent and achieve decontamination through the emulsification and dispersion of surfactants and the softening effect of alkaline additives on carbon deposits. They have significant advantages such as non-flammability, low toxicity, and environmental friendliness, and have become the mainstream direction of current aircraft engine cleaning agent research and development.

[0004] However, existing water-based cleaning agents still have several shortcomings in practical applications. Many commercially available water-based cleaning agents have limited ability to remove dense carbon deposits formed by high-temperature sintering, making it difficult to completely break down carbonaceous deposits. Repeated cleaning or strong mechanical scrubbing is often required, which not only reduces maintenance efficiency but may also cause secondary damage to precision components. Furthermore, some cleaning agents use highly alkaline additives such as sodium hydroxide and sodium carbonate to enhance their ability to break down carbon deposits. These strong alkaline components pose varying degrees of corrosion risk to aluminum alloys, titanium alloys, and nickel-based alloys widely used in engines, especially significantly damaging the oxide film on the surface of aluminum alloys, potentially reducing component fatigue life. In addition, inorganic additives commonly used in existing water-based cleaning agents, such as phosphates, silicates, and molybdates, leave solid ash residues after cleaning and drying. These residues may sinter to form new deposits during subsequent high-temperature engine operation or detach and enter the fuel system, causing blockages. Airworthiness standards such as the US military standard MIL-PRF-85704C and the Chinese military standard GJB 2841 have strict limits on the ash content of cleaning agents (usually requiring it not to exceed 0.05%), which places high technical requirements on formulation design.

[0005] Chinese patent CN105969545A, "An Aircraft Engine Cleaning Agent and Its Preparation Method", discloses an aircraft engine cleaning agent and its preparation method, including 10-20 parts of carbon deposit cleaning agent, 35-50 parts of detergent and 6-12 parts of corrosion inhibitor. It also discloses that the detergent contains dichromate and silicate components. The high content of inorganic salts results in a high risk of solid ash residue, which requires further optimization.

[0006] Therefore, it is of great significance to research and develop an aircraft engine internal cleaning agent that can efficiently remove oil and carbon deposits, is low in corrosiveness, and has low ash content, as well as its preparation method. Summary of the Invention

[0007] The purpose of this invention is to provide an internal cleaning agent for aircraft engines and its preparation method, so as to solve the problem mentioned in the background art that the high inorganic salt content of existing aircraft engine cleaning agents leads to a high risk of solid ash residue.

[0008] To achieve the above objectives, the present invention provides the following technical solution: An internal cleaning agent for aircraft engines, comprising, by weight, the following components: 2-5 parts sodium dodecylbenzenesulfonate, 2-5 parts isomeric alcohol ether, 5-10 parts fatty alcohol polyoxyethylene ether, 2-5 parts chelating dispersant, 3-8 parts multi-component corrosion inhibitor, 3-8 parts organic solvent, and 45-70 parts deionized water.

[0009] This invention utilizes sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ether to rapidly form a dense mixed micelle in an aqueous solution. This emulsifies oil stains, solubilizes them within the hydrophobic core of the micelles, prevents redeposition, and enhances the cleaning agent's detergency. Meanwhile, the isomeric alcohol ether reduces the solid-liquid interfacial tension, allowing the cleaning solution to rapidly spread and penetrate the microstructure between the carbon deposit layer and the metal substrate, disrupting the adhesion between the carbon deposit layer and the substrate, thereby achieving efficient stripping. The combination of the three surfactants produces a significant synergistic effect. Under dynamic cleaning conditions, sodium dodecylbenzenesulfonate provides a rapid interfacial adsorption response, the isomeric alcohol ether provides excellent dynamic wetting properties, and the fatty alcohol polyoxyethylene ether provides stable emulsion maintenance. Each of the three functions works together to ensure efficient oil and carbon removal under complex cleaning conditions.

[0010] Preferably, the chelating dispersant is one or more of sodium citrate, disodium EDTA, tetrasodium glutamate diacetate, and tetrasodium iminodisuccinate.

[0011] The preferred chelating dispersant of this invention is one or more of sodium citrate, disodium EDTA, tetrasodium glutamate diacetate, and tetrasodium iminodisuccinate. These substances are organic chelating agents, and the functional groups in their molecules can form stable five-membered or six-membered ring chelates with metal ions such as calcium, magnesium, and iron, preventing them from reacting with surfactants and thus ensuring the stability of cleaning performance.

[0012] Preferably, the chelating dispersant is sodium citrate or disodium EDTA.

[0013] The preferred chelating dispersant of this invention is a compound chelating system of sodium citrate and disodium EDTA. Sodium citrate has a strong chelating ability for calcium ions and is suitable for softening water. Disodium EDTA has a strong chelating ability for heavy metal ions and is suitable for breaking down metal oxide components in carbon deposits. The compound use is beneficial to achieve comprehensive chelation of various metal ions and improve the hard water adaptability and carbon deposit breaking ability of the cleaning agent.

[0014] Preferably, the multi-element corrosion inhibitor is obtained by compounding organic amine corrosion inhibitors and carboxylic acid corrosion inhibitors.

[0015] This invention preferably employs an organic amine-carboxylic acid multi-element corrosion inhibition system. The organic amine provides an alkaline environment, and through the lone pair electrons in the amino group forming coordinate bonds with the empty d orbitals on the metal surface, chemical adsorption occurs, blocking the contact between water molecules, dissolved oxygen, and corrosive ions and the metal surface, thereby inhibiting the occurrence of electrochemical corrosion reactions. In a weakly alkaline environment, the carboxyl group is neutralized into a carboxylate anion, which electrostatically adsorbs onto the cation sites on the metal surface, forming a hydrophobic organic protective film. When organic amine and carboxylic acid coexist, the anions and cations in the system can form a multi-layered protective film through alternating adsorption, which is dense and complete, significantly improving the coverage of the metal surface and enhancing the corrosion inhibition effect.

[0016] More preferably, the organic amine corrosion inhibitor is one or more of monoethanolamine, triethanolamine, and diethylene glycolamine.

[0017] More preferably, the carboxylic acid corrosion inhibitor is one or more of sebacic acid, boric acid, and citric acid.

[0018] Preferably, the organic solvent is diethylene glycol butyl ether and / or diethylene glycol tert-butyl ether. Preferably, the pH value of the cleaning agent is 8.5-10.

[0019] In addition, the present invention also provides a method for preparing an internal cleaning agent for aircraft engines.

[0020] A method for preparing an aircraft engine internal cleaning agent according to any one of the above claims, comprising the following steps: S1. Weigh each component according to the required ratio, disperse the multi-component corrosion inhibitor in 60% deionized water under continuous stirring, stir to dissolve, and obtain a multi-component corrosion inhibitor solution; S2. While stirring, add sodium dodecylbenzenesulfonate, isomeric alcohol ether, and fatty alcohol polyoxyethylene ether to the multi-element corrosion inhibitor solution obtained in S1, heat and mix, then add chelating dispersant and organic solvent in sequence, heat to dissolve, add deionized water to make up the balance, adjust the pH value to 8.5-10, let stand, defoam naturally, filter, and the aircraft engine internal cleaning agent is obtained.

[0021] Preferably, the stirring and dissolving speed in S1 is 100-300 rpm, and the time is 5-10 min.

[0022] Preferably, the heating and mixing temperature in S2 is 30-40℃, and the time is 10-20 min.

[0023] Preferably, the heating and dissolution temperature in S2 is 40-50°C, and each component is stirred for 2-3 minutes after addition until completely dissolved.

[0024] Compared with the prior art, the beneficial effects of the present invention are: The aircraft engine internal cleaning agent of this invention comprises sodium dodecylbenzenesulfonate, isomeric alcohol ethers, fatty alcohol polyoxyethylene ethers, chelating dispersants, multi-component corrosion inhibitors, organic solvents, and water. The organic solvent, assisted by the isomeric alcohol ethers, rapidly penetrates into the carbon deposit layer, dissolving soluble components and making the dense carbon deposits loose and porous. The isomeric alcohol ethers, leveraging their low dynamic surface tension, quickly wet the interface between the carbon deposits and the metal, reducing adhesion. Sodium dodecylbenzenesulfonate and fatty alcohol polyoxyethylene ethers form mixed micelles, emulsifying and dispersing oil stains. Simultaneously, through entrainment and emulsification, the softened carbon deposits are peeled off from the metal surface and stably dispersed in the aqueous phase. This is achieved through the synergistic effect of the three surfactants. In combination, a complete decontamination chain is formed in three dimensions: emulsification, penetration, and dispersion, further enhancing the decontamination ability. The chelating dispersant complexes calcium and magnesium ions in the water to ensure the cleaning efficiency and stability of the surfactant, while dispersing the detached dirt particles to prevent redeposition. The multi-element corrosion inhibitor forms a multi-layer adsorption film on the metal surface, protecting the metal substrate from corrosion during the cleaning process. Without the use of inorganic salt corrosion inhibitors, a highly efficient oil and carbon deposit removal agent with low corrosivity and low ash content for aircraft engines is obtained, which can meet the requirements of aircraft engine airworthiness standards. The preparation process is mild and simple, with low energy consumption and high efficiency, and has excellent application value, making it suitable for industrial production. Detailed Implementation

[0025] To better illustrate the objectives, technical solutions, and advantages of this invention, the following embodiments are provided. Obviously, the following embodiments are only a part of the embodiments of this invention, and not all of them; these embodiments do not imply any limitation on this invention. Those skilled in the art should understand that these embodiments are only used to illustrate the technical effects of this invention, and not to limit the scope of protection of this invention.

[0026] Experimental methods in the following examples, unless otherwise specified, are generally performed under standard conditions or as recommended by the manufacturer. These examples are primarily intended to provide a better understanding of the analytical methods of this invention and do not exhaustively cover all possible procedures.

[0027] All raw materials used in the examples are commercially available; unless otherwise specified, the reagents, methods and equipment used in this invention are conventional reagents, methods and equipment in this technical field.

[0028] Example 1 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Disperse 3 parts of triethanolamine and 1 part of monoethanolamine in 60% of the total amount of 60 parts of deionized water under continuous stirring. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 3 parts isomeric alcohol ether, and 8 parts fatty alcohol polyoxyethylene ether to the multi-component corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 2 parts sodium citrate, 1 part disodium EDTA, and 5 parts diethylene glycol butyl ether in sequence. Raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0029] Example 2 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. While continuously stirring, disperse 3 parts of triethanolamine in 60% of the total 60 parts of deionized water. Stir at 200 rpm until completely dissolved. Add 1 part of boric acid and 0.5 parts of citric acid (neutralize the citric acid with a small amount of monoethanolamine to pH≈7 before adding). Continue stirring to dissolve for 8 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 3 parts sodium dodecylbenzenesulfonate, 4 parts isomeric alcohol ether, and 9 parts fatty alcohol polyoxyethylene ether to the multi-element corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 2 parts sodium citrate, 2 parts disodium EDTA, and 5 parts diethylene glycol tert-butyl ether in sequence. Raise the temperature to 40°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with triethanolamine and citric acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0030] Example 3 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. While continuously stirring, disperse 4 parts of triethanolamine in 60% of the total 60 parts of deionized water. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and 0.5 parts of citric acid (neutralize the citric acid with a small amount of monoethanolamine to pH≈7 before adding). Continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 4 parts isomeric alcohol ether, and 7 parts fatty alcohol polyoxyethylene ether to the multi-element corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 3 parts sodium citrate, 2 parts disodium EDTA, and 7 parts diethylene glycol butyl ether in sequence. Raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with triethanolamine and citric acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0031] Comparative Example 1 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Disperse 3 parts of triethanolamine and 1 part of monoethanolamine in 60% of the total amount of 60 parts of deionized water under continuous stirring. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 1 part sodium dodecylbenzenesulfonate, 3 parts isomeric alcohol ether, and 8 parts fatty alcohol polyoxyethylene ether to the multi-element corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 2 parts sodium citrate, 1 part disodium EDTA, and 5 parts diethylene glycol butyl ether in sequence. Raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0032] The main difference between this comparative example and Example 1 is that this comparative example has insufficient sodium dodecylbenzenesulfonate.

[0033] Comparative Example 2 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Disperse 3 parts of triethanolamine and 1 part of monoethanolamine in 60% of the total amount of 60 parts of deionized water under continuous stirring. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 1 part isomeric alcohol ether, and 8 parts fatty alcohol polyoxyethylene ether to the multi-component corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 2 parts sodium citrate, 1 part disodium EDTA, and 5 parts diethylene glycol butyl ether in sequence. Raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0034] The main difference between this comparative example and Example 1 is that this comparative example has insufficient isomeric alcohol ethers.

[0035] Comparative Example 3 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Disperse 3 parts of triethanolamine and 1 part of monoethanolamine in 60% of the total amount of 60 parts of deionized water under continuous stirring. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 3 parts isomeric alcohol ether, and 3 parts fatty alcohol polyoxyethylene ether to the multi-component corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 2 parts sodium citrate, 1 part disodium EDTA, and 5 parts diethylene glycol butyl ether in sequence. Raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0036] The main difference between this comparative example and Example 1 is that this comparative example has insufficient fatty alcohol polyoxyethylene ether.

[0037] Comparative Example 4 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Disperse 3 parts of triethanolamine and 1 part of monoethanolamine in 60% of the total amount of 60 parts of deionized water under continuous stirring. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 3 parts isomeric alcohol ether, and 12 parts fatty alcohol polyoxyethylene ether to the multi-component corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 2 parts sodium citrate, 1 part disodium EDTA, and 5 parts diethylene glycol butyl ether in sequence. Raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0038] The main difference between this comparative example and Example 1 is that the fatty alcohol polyoxyethylene ether in this comparative example is in excess.

[0039] Comparative Example 5 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Disperse 3 parts of triethanolamine and 1 part of monoethanolamine in 60% of the total amount of 60 parts of deionized water under continuous stirring. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 3 parts isomeric alcohol ether, and 8 parts fatty alcohol polyoxyethylene ether to the multi-component corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Add 5 parts diethylene glycol butyl ether and heat to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are fully mixed, make up the difference with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to defoam naturally, and filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0040] The main difference between this comparative example and Example 1 is that no chelating dispersant is added to this comparative example.

[0041] Comparative Example 6 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Disperse 3 parts of triethanolamine and 1 part of monoethanolamine in 60% of the total amount of 60 parts of deionized water under continuous stirring. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 3 parts isomeric alcohol ether, and 8 parts fatty alcohol polyoxyethylene ether to the multi-component corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 4 parts sodium citrate, 3 parts disodium EDTA, and 5 parts diethylene glycol butyl ether in sequence. Raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0042] The main difference between this comparative example and Example 1 is that the chelating dispersant in this comparative example is in excess.

[0043] Comparative Example 7 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Under continuous stirring, disperse 2 parts of sodium carbonate, 1 part of potassium dichromate, and 1 part of sodium silicate in 60% of the total volume of 60 parts of deionized water. Stir at 200 rpm until completely dissolved to obtain a corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 3 parts isomeric alcohol ether, and 8 parts fatty alcohol polyoxyethylene ether to the corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Then, add 2 parts sodium citrate, 1 part disodium EDTA, and 5 parts diethylene glycol butyl ether in sequence. Raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are thoroughly mixed, add the remainder with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to allow natural defoaming. Filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0044] The main difference between this comparative example and Example 1 is that this comparative example uses an inorganic salt corrosion inhibitor.

[0045] Comparative Example 8 A method for preparing an internal cleaning agent for an aircraft engine includes the following steps: S1. Weigh each component according to the required ratio. Disperse 3 parts of triethanolamine and 1 part of monoethanolamine in 60% of the total amount of 60 parts of deionized water under continuous stirring. Stir at 200 rpm until completely dissolved. Add 1 part of sebacic acid and continue stirring to dissolve for 7 minutes until all carboxylic acid components are completely dissolved to obtain a multi-component corrosion inhibitor solution. S2. While stirring, add 4 parts sodium dodecylbenzenesulfonate, 3 parts isomeric alcohol ether, and 8 parts fatty alcohol polyoxyethylene ether to the multi-element corrosion inhibitor solution obtained in S1. Heat and mix at 35°C for 15 minutes until the system presents a uniform transparent or slightly milky white appearance. Add 2 parts sodium citrate and 1 part disodium EDTA in sequence, and raise the temperature to 45°C. Stir for 2-3 minutes after each component is added until completely dissolved. After all solid components are completely dissolved and liquid components are fully mixed, make up the difference with deionized water. Adjust the pH value to 8.5-10 with monoethanolamine and sebacic acid. Let stand to defoam naturally, and filter through a 200-mesh filter to obtain the aircraft engine internal cleaning agent.

[0046] The main difference between this comparative example and Example 1 is that no organic solvent is added to this comparative example.

[0047] Performance testing: Performance tests were conducted on Examples 1-3 and Comparative Examples 1-8, and the specific test methods are as follows: Oil removal rate test: The oil removal rate test was conducted according to the test method in the People's Republic of China Machinery Industry Standard JB / T 4323—2019 "Water-based Metal Cleaning Agents". The test piece was a 304 stainless steel sheet with dimensions of 50mm × 25mm × 2mm. The initial mass was recorded. Standard oil was evenly coated onto the surface of the test piece, and it was placed in a desiccator at room temperature for at least 2 hours to allow the oil film to stabilize. The mass after coating was then recorded. Working solutions were prepared by mixing the cleaning agent samples from Examples 1-3 and Comparative Examples 1-8 with tap water at a ratio of 1:20. The samples were then completely immersed in ultrasonic cleaning at a frequency of 40kHz, a power of 200W, a cleaning temperature of 50℃, and a cleaning time of 10 minutes. After cleaning, the test pieces were rinsed with deionized water, dehydrated with anhydrous ethanol, and then dried in an oven at 100℃±2℃ for 30 minutes. After removal, they were placed in a desiccator to cool to room temperature, and the mass after cleaning was recorded using an analytical balance. Three parallel determinations were performed, and the average value was taken.

[0048] The oil removal rate is calculated using the following formula: Degreasing rate (%) = (Weight after oiling - Weight after cleaning) / (Weight after oiling - Initial weight) × 100% Carbon deposit removal rate test: The test piece was made of 304 stainless steel, measuring 50mm × 25mm × 2mm. The initial mass was recorded. Aviation kerosene was used as a carbon deposit precursor. The test piece was immersed in aviation kerosene to ensure a uniform oil film adhered to its surface. After draining, it was placed in a muffle furnace and sintered at 550℃ for 2 hours to fully carbonize the oil film and form a dense carbon deposit layer. This immersion-sintering process was repeated 2 to 3 times until a uniform, dense, and consistent carbon deposit layer was formed on the test piece surface. After cooling, the mass of the carbon deposited test piece was recorded, and the initial carbon deposit amount was calculated. Working solutions were prepared by mixing the cleaning agent samples from Examples 1-3 and Comparative Examples 1-8 with tap water at a ratio of 1:20. The samples were then completely immersed in ultrasonic cleaning at a frequency of 40kHz, a power of 200W, a cleaning temperature of 45℃, and a cleaning time of 15 minutes. After cleaning, the test pieces were thoroughly rinsed with deionized water and dried in an oven at 100℃±2℃ for 30 minutes. The mass was then recorded after cooling. The measurements were performed in three parallel trials, and the average value was taken.

[0049] Carbon deposit removal rate is calculated using the following formula: Carbon removal rate (%) = (Mass of sample before cleaning - Mass of sample after cleaning) / (Mass of sample before cleaning - Initial mass of sample) × 100% Corrosion test: The corrosion test was conducted according to ASTM F483, "Standard Practice for Total Immersion Corrosion Test for Aircraft Maintenance Chemicals," using 7075-T6 aluminum alloy specimens measuring 50mm × 25mm × 2mm. The mass and surface area of ​​the specimens were measured using an analytical balance and vernier calipers for corrosion rate calculation. Working solutions were prepared by mixing the cleaning agent samples from Examples 1-3 and Comparative Examples 1-8 with tap water at a ratio of 1:20. The treated specimens were completely immersed in the working solution at a temperature controlled at 50℃ ± 1℃ for 24 hours. After immersion, the specimens were removed and gently rinsed with deionized water to remove any remaining cleaning solution. Corrosion products were gently removed from the surface using a soft brush or wiping material (care should be taken not to damage the uncorroded metal substrate). The treated specimens were then immersed in anhydrous ethanol for dehydration, removed, and dried in an oven at 100℃ ± 2℃ for 30 minutes. After cooling, the final mass was measured. The measurements were performed in three parallel trials, and the average value was taken.

[0050] The corrosion rate is calculated using the following formula: Corrosion rate (mg / cm) 2 •24h) = (Initial mass - Final mass) / Surface area of ​​the specimen Ash content test: The ash content test was conducted according to the method specified in the US military standard MIL-PRF-85704C "Cleaning Compound, Engine Gas Path". 10g of the concentrated cleaning agent samples from Examples 1-3 and Comparative Examples 1-8 were accurately weighed using an analytical balance and the mass was recorded. The samples were heated at a low temperature to remove moisture. After the moisture had completely evaporated, the crucible was transferred to a high-temperature muffle furnace and ignited at 550℃±25℃ for 2 hours. After ignition, the power was turned off, and the crucible was allowed to cool naturally in the muffle furnace to approximately 200℃. Then, the crucible was transferred to a desiccator to cool to room temperature and weighed using an analytical balance. The weighed crucible was then placed back into the muffle furnace and ignited at the same temperature for 30 minutes. After cooling, it was weighed again. This process was repeated until the difference between two consecutive weighings did not exceed 0.5mg, which was considered constant weight.

[0051] Ash content is calculated using the following formula: Ash content (%) = (mass of crucible after ignition - mass of empty crucible) / initial mass of sample × 100% The specific test results of Examples 1-5 and Comparative Examples 1-8 are shown in the table below: Table 1. Specific test results of Examples 1-3 and Comparative Examples 1-8 As shown in Table 1, the degreasing rate of Examples 1-3 was ≥95%, the carbon removal rate was ≥85%, and the aluminum alloy corrosion rate was ≤0.1mg / cm³. 2 • The ash content was strictly controlled below 0.05% over 24 hours, indicating that the aircraft engine internal cleaning agent of this invention can efficiently remove oil and carbon deposits, has low corrosivity, and provides excellent protection for aluminum alloys, significantly superior to inorganic salt corrosion inhibitor systems. At the same time, the ash content is only 0.015%-0.023%, far below the military standard limit of 0.05%, which meets the requirements of aircraft engine airworthiness standards and has excellent application value.

[0052] Comparative Example 1: Insufficient sodium dodecylbenzenesulfonate resulted in a total surfactant concentration below the critical micelle concentration, preventing micelle formation, eliminating emulsification and solubilization benefits, and drastically reducing detergency. The oil removal rate was only 60.2%, and the carbon removal rate was 57.5%, failing to meet aviation cleaning requirements. Comparative Example 2: Insufficient isomeric alcohol ether significantly weakened penetration, reducing the carbon removal rate to 79.8%. Comparative Example 3: Insufficient fatty alcohol polyoxyethylene ether led to a loss of emulsification ability due to insufficient nonionic surfactants. Oil residue could not be stably suspended after detachment, resulting in significant redeposition and an oil removal rate of only 67.2%. Comparative Example 4: Excessive fatty alcohol polyoxyethylene ether performed excellently in performance tests, but its effectiveness decreased during actual storage. The system exhibited a gel phase, with a sharp increase in viscosity and a significant decrease in cloud point at low temperatures, resulting in severely deteriorated low-temperature fluidity and rendering it unusable in practice. Comparative Example 5, lacking a chelating dispersant, lacked the ability to disperse dirt, leading to a decrease in the cleaning agent's ability to remove carbon deposits. Furthermore, due to the absence of a chelating dispersant, calcium and magnesium ions in tap water reacted with surfactants to form insoluble soap scum, depositing on the component surface and forming white spots, severely affecting appearance. Comparative Example 6 contained an excessive amount of chelating dispersant, resulting in an ash content of 0.062%, failing to meet military standard certification. Comparative Example 7 used an inorganic salt corrosion inhibitor, which effectively removed oil and carbon deposits, but its corrosion rate on aluminum alloys reached as high as 0.48 mg / cm³. 2 • After 24 hours, the ash content was as high as 0.28%, which completely fails to meet airworthiness requirements; in comparison, without the addition of organic solvents, the cleaning agent's ability to dissolve carbon deposits was significantly reduced, with a carbon removal rate of only 57.8%, which cannot meet the internal cleaning requirements of aircraft engines.

[0053] In summary, this invention provides an internal cleaning agent for aircraft engines prepared from sodium dodecylbenzenesulfonate, isomeric alcohol ethers, fatty alcohol polyoxyethylene ethers, chelating dispersants, multi-component corrosion inhibitors, organic solvents, and deionized water. The organic solvent, aided by isomeric alcohol ethers, rapidly dissolves dense carbon deposits. The three surfactants work synergistically to form a complete cleaning chain encompassing emulsification, penetration, and dispersion, further enhancing cleaning power. The chelating dispersant ensures cleaning efficiency and stability, preventing redeposition. The multi-component corrosion inhibitor protects the metal matrix. Without the use of inorganic salt corrosion inhibitors, this agent efficiently removes oil and carbon deposits, ensuring low corrosivity and low ash residue, meeting the airworthiness standards for aircraft engines. The preparation process is mild and simple, with low energy consumption and high efficiency, demonstrating excellent application value and suitability for industrial production.

[0054] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. An internal cleaning agent for aircraft engines, characterized in that, By weight, it includes the following components: 2-5 parts sodium dodecylbenzenesulfonate, 2-5 parts isomeric alcohol ether, 5-10 parts fatty alcohol polyoxyethylene ether, 2-5 parts chelating dispersant, 3-8 parts multi-component corrosion inhibitor, 3-8 parts organic solvent, and 45-70 parts deionized water.

2. The aircraft engine internal cleaning agent and its preparation method according to claim 1, characterized in that: The chelating dispersant is one or more of sodium citrate, disodium EDTA, tetrasodium glutamate diacetate, and tetrasodium iminodisuccinate.

3. The aircraft engine internal cleaning agent according to claim 1, characterized in that: The multi-element corrosion inhibitor is obtained by compounding organic amine corrosion inhibitors and carboxylic acid corrosion inhibitors.

4. The aircraft engine internal cleaning agent according to claim 3, characterized in that: The organic amine corrosion inhibitor is one or more of monoethanolamine, triethanolamine, and diethylene glycolamine.

5. The aircraft engine internal cleaning agent according to claim 3, characterized in that: The carboxylic acid corrosion inhibitor is one or more of sebacic acid, boric acid, and citric acid.

6. The aircraft engine internal cleaning agent according to claim 1, characterized in that: The organic solvent is diethylene glycol butyl ether and / or diethylene glycol tert-butyl ether.

7. The aircraft engine internal cleaning agent according to claim 1, characterized in that: The pH value of the cleaning agent is 8.5-10.

8. A method for preparing an internal cleaning agent for an aircraft engine according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Weigh each component according to the required ratio, disperse the multi-component corrosion inhibitor in 60% deionized water under continuous stirring, stir to dissolve, and obtain a multi-component corrosion inhibitor solution; S2. While stirring, add sodium dodecylbenzenesulfonate, isomeric alcohol ether, and fatty alcohol polyoxyethylene ether to the multi-element corrosion inhibitor solution obtained in S1, heat and mix, then add chelating dispersant and organic solvent in sequence, heat to dissolve, add deionized water to make up the balance, adjust the pH value to 8.5-10, let stand, defoam naturally, filter, and the aircraft engine internal cleaning agent is obtained.

9. The method for preparing an internal cleaning agent for an aircraft engine according to claim 8, characterized in that: The stirring and dissolving speed described in S1 is 100-300 rpm, and the time is 5-10 min.

10. The aircraft engine internal cleaning agent and its preparation method according to claim 8, characterized in that: The heating and mixing temperature in S2 is 30-40℃, and the time is 10-20 min; the heating and dissolving temperature in S2 is 40-50℃, and each component is stirred for 2-3 min after addition until completely dissolved.

Images