Aerospace

Aviation lubricating oil: generally refers to the oil used for aircraft and ground airport equipment, mainly including aviation engine oil, aviation transmission system oil, and aviation lubricating grease.

Different aviation engine manufacturers have introduced and developed their own aviation engine oil specification requirements, such as Pratt&Whitney's PWA521 specification, GE's D50TF1 specification, and Allison's EMS53 specification. The SAEE34 organization has also developed a core technical specification for aviation gas turbines, SAEAS5780, This specification specifies the basic physical, chemical, and other properties of gas turbine oil with a viscosity grade of 5mm2/s applicable to turbo engines or turbo driven ships and industrial equipment.

At present, the main international specifications for aviation engine oil are still dominated by the US military standard specifications, and this type of oil needs to focus on considering the storage stability, oxidation stability, and corrosiveness of the oil under high and low temperature conditions.

The aviation engine that was originally used as aircraft power was a piston type engine. After experiencing the baptism of World War II, this piston type engine technology developed to its peak; With the global economic growth, this piston engine is no longer suitable for high-speed, high endurance, and low energy consuming large aircraft, such as transport and passenger planes. With the emergence of aviation turbine engines, it has gradually withdrawn from the aviation transportation field. As a result, human aviation began to enter the era of jet technology.

After about 60 years of technological progress, turbine engines have developed from turbojet engines to turbofan, greatly improving the safety, stability and economy of aircraft.

With the development and progress of aeroengine technology and the improvement of performance, the severity of the engine is also increasing under working conditions. For example, some parts of modern turbofan need to work stably and reliably at about 1200~1500 ℃, and the required quality level of aeroengine lubricating oil is also improved. In order to meet the reliable requirements of aviation engines for lubricating oil, aviation engine oil standards have also emerged.

Aviation engine oil, as the blood of aviation engines, is a high-performance aviation engine lubricating oil that not only provides sufficient lubrication for various moving parts of the aircraft engine, but also provides sufficient sealing and heat dissipation effects to ensure the safe and stable long-term endurance of the aircraft engine under high-speed and high temperature conditions.

1.1 Specification and Main Performance of Aviation Engine Oil

1.1.1 Engine lubricating oil system

To ensure the safe and stable operation of aviation engines, it is necessary to use a lubrication system to provide a stable flow of lubricating oil to various lubrication parts of the engine. The design of the lubrication system can be divided into two stages. Engines put into use before the 1980s mostly used traditional lubrication systems, as shown in Figure 3. The new generation of aviation engine lubrication system is further improved on the basis of traditional lubrication system, making it work more safely and reliably to ensure the normal supply of lubricating oil.

1.1.2 Specification of aviation engine oil

Aviation engine lubricating oil effectively lubricates the lubricating parts of the engine through the lubrication system, while also taking away a large amount of heat generated by the combustion of fuel absorbed by the lubricating components, ensuring stable operation of the engine at a certain operating temperature. Therefore, during the circulation process of lubricating oil, it needs to undergo a continuous cycle of heat absorption, heating up, oxidation, and cooling. During this process, the oil product tends to experience reactions such as evaporation, coking, and corrosion. This puts forward very strict requirements for aviation engine lubricating oil. Measuring whether a lubricating oil can meet the basic requirements of aviation engines is mainly limited by specifications and standards.

The development and changes in the specifications of aviation engine oil are in line with the development of aviation engine technology. Different aviation engine manufacturers have introduced and developed their own aviation engine oil specification requirements, such as Pratt&Whitney's PWA521 specification, GE's D50TF1 specification, and Allison's EMS53 specification. The SAEE34 organization has also developed a core technical specification for aviation gas turbines, SAEAS5780, This specification specifies the basic physical, chemical, and other properties of gas turbine oil with a viscosity grade of 5mm2/s applicable to turbo engines or turbo driven ships and industrial equipment. But overall, they are all based on US military standards, and the required base oil has gradually developed from the initial mineral oil type and semi synthetic type to the double ester type synthetic oil, until the current new pentyl polyol ester synthetic oil. The US military aviation engine oil standard is divided into two specifications based on the viscosity of the oil at 100 ℃. One is the MIL-L-7808 specification, which specifies two viscosity levels: 3mm2/s and 4mm2/s. The former is suitable for general applications, while the latter is suitable for applications with higher thermal stability requirements. This specification was released in 1951 and has been revised multiple times to this day; The second is the MIL-L-23699 specification, which specifies a viscosity grade of 5mm2/s. This specification was released in 1963 and has been gradually improved in multiple versions. The specified oil products include three types: standard type (STD), rust proof type (C/I), and high-temperature stable type (HTS). The two specifications currently in use are the MIL-PRF-7808L and MIL-PRF-23699F specifications released in May 1997.

1.2 Aviation Engine Oil Products and Manufacturers

Domestic aviation engine oils are basically divided into two types: synthetic and mineral.

Aviation hydraulic oil/aviation lubricating oil

Aviation hydraulic oil is mainly used as a working fluid for the transmission mechanism of aviation hydraulic systems, and is also an ideal working medium for various hydraulic machinery with high requirements. It has good high and low temperature performance, viscosity temperature resistance, shear resistance, oxidation stability, and hydraulic transmission performance, with a service temperature of -54 ℃ -135 ℃. The antioxidant stability can meet the usage requirements of various new aircraft hydraulic systems.

Since the 1950s, the US Air Force has been committed to the research of advanced aviation hydraulic fluids. From petroleum based type to phosphate ester type, and then to poly α- The synthesis of hydrocarbon based olefins (PAO) and the improvement of flame resistance have always been the main driving force for the development of new aviation hydraulic oils. In addition, due to the increasing awareness of environmental protection, the biodegradability and low toxicity of hydraulic oil have become increasingly important, and replacing rustproof hydraulic oil with aviation hydraulic oil for storing parts has become a trend. In the future, with the continuous improvement of aircraft performance, high-temperature hydraulic oil will also become the development direction.

2.1 Specification of aviation hydraulic oil

No. 15 aviation hydraulic oil GJB1177-1991

Mainly used as a working fluid for aviation hydraulic transmission mechanisms, it can replace domestic No. 10 and No. 12 aviation hydraulic oil and American MIL-H-5606E hydraulic oil.

No. 10 aviation hydraulic oil (Sky) SH0358-1992 is mainly used as a working fluid for aviation hydraulic transmission mechanisms, and can also be used as a working fluid for other high-performance hydraulic systems. Such as CNC machine tools, acetamide circulation pumps, high-pressure ethylene delivery pumps and ship cranes, deck machinery, excavators, windlasses, large cranes, radar cars and railways, electrical switches, etc. Due to its low freezing point, this product can also be used in various equipment mentioned above in extremely cold regions and can replace the use of inverted cooling oil. The operating temperature is above -70 ℃. No. 10 aviation hydraulic oil (ground oil) Q/SYYM0024-2000

This product is mainly used as a working fluid for various hydraulic systems with high requirements, as well as various hydraulic mechanical equipment in cold areas and airport ground. Such as CNC machine tools, ethanolamine circulation pumps, high-pressure ethylene delivery pumps, ship cranes, deck machinery, excavators, anchor winches, large cranes, etc. The operating temperature is above -50 ℃.2.2航空液压油产品及生产

China Petroleum Yumen Refining and Chemical Complex

With the strong support of China National Petroleum Corporation, the General Rear of the People's Liberation Army, the Air Force, and the stationed military representative office, the Yumen Refining and Chemical Complex and the Air Force Oil Research Institute have been jointly developing the No. 15 aviation hydraulic oil since 1988. The developed oil has been analyzed and evaluated to meet all technical specifications of the US military MIL-H-5606E standard, and has passed bench tests and flight and trial tests of J-8 and other aircraft models, which can replace the domestically produced No. 10 The production process of No. 12 aviation hydraulic oil has successfully passed the appraisal of the Domestic Aviation Oil Appraisal Committee, and it is unanimously believed that the production process of No. 15 aviation hydraulic oil at Yumen Refinery and Chemical Complex is stable, and the product name and indicators meet the requirements. Especially, the shear stability, oxidation stability, and low-temperature resistance have significantly improved compared to No. 12 aviation hydraulic oil, and there is no significant difference compared to the American MIL-H-5606E standard hydraulic oil, Agree to put into production and provide for user use. In 2000, an overall renovation was carried out on the blending and filling system, achieving automated filling and packaging of oil products in clean factories, further stabilizing product quality and completely replacing imported aviation hydraulic oil. At the same time, it can meet the needs of military and civil aviation.

Aviation lubricating grease/aviation lubricating oil

Aviation lubricating grease is mainly used for aircraft instruments and control components, with strict low-temperature performance requirements. At the same time, there are also some high-temperature greases used on landing and motion components.

3.1 Specifications and Products

No.2 low-temperature lubricating grease (produced by Yumen)

Used for the protection and lubrication of aircraft control rod systems, lubrication of various precision instruments and radio equipment, as well as rolling bearings, sliding bearings, and other wear parts of various mechanical equipment with light loads, high speeds, and a wide temperature range (-60 ℃~120 ℃).

No.2 aviation lubricating grease (produced in Fushun)

No.2 aviation lubricating grease has excellent low temperature performance, high temperature performance, and water resistance, and can be used for lubrication of ball bearings operating in a wide temperature range, with temperatures ranging from -50 ° C to 120 ° C. It has excellent high and low temperature performance, mechanical stability, colloidal stability, and oxidation stability.

Suitable for lubrication of bearings, gears, and control mechanisms of aviation motors and micro motors, as well as assembly and connection parts, as well as certain instruments and meters; Aviation lubricating grease is also suitable for the lubrication of high-speed ball bearings; The lubrication life of the grinding machine spindle at a speed of 5000-20000r/min is three years, which is six times that of the 2 # and 3 # spindle. Replacing 5 #, 7 #, and 10 # spindle oil with aviation lubricating grease can significantly reduce lubrication costs. Aviation lubricating grease is used for spinning machine spindle bearings with a continuous working time of 2000/min, and the greasing interval can be extended to six months. Suitable for 3600r/min air spinning separated spindle bearings, the interval for supplementing lubricating grease can be extended to three months. Aviation lubricating grease can be used for lubrication of ball bearings (such as DC blades) of mechanical and electrical equipment working outdoors in cold regions, as well as bearings of motors for low-temperature fluid transfer pumps (such as methane and ethane reflux pumps);

7007 and 7008 aviation lubricating grease (produced by Yiping)

Specially designed for aviation lubrication, it is a multi-purpose aviation lubricating grease suitable for the lubrication of aviation motor bearings and gears, operating mechanism fulcrums, assembly connections, and certain instruments and meters. It is also suitable for the lubrication of high-speed ball bearings.

This product is also suitable for non aviation applications, such as grinding machine spindles with a speed range of 5000r/min to 20000r/min, spinning and twisting machine spindle bearings with a continuous speed range of 2000r/min, separated spindle bearings with a speed range of 3600r/min, and electromechanical ball bearings (such as DC generators) and instrument motor bearings for outdoor work in cold areas Lubrication of bearings for high-speed household micro motors (such as home crushers, electric shavers) and low-temperature liquid delivery pumps (such as methane and ethane reflux pumps).

Wide temperature aviation lubricating grease (produced by China Petroleum and Chemical Research Institute)

The applicable temperature (-60 ℃~300 ℃) is specifically developed for aerospace equipment, and the specific performance and specifications are confidential.

Extreme pressure and wear resistance performance indicators and significance of lubricating grease/aviation lubricating oil

For the lubrication of equipment with high loads, certain extreme pressure or anti wear additives are added to the lubricating grease to improve the extreme pressure and anti wear performance of the grease. The extreme pressure and anti wear performance of lubricating grease is a very important indicator. Poor extreme pressure and anti wear performance can lead to severe wear of equipment,

For the lubrication of equipment with high loads, certain extreme pressure or anti wear additives are added to the lubricating grease to improve the extreme pressure and anti wear performance of the grease. The extreme pressure and wear resistance performance of lubricating grease is a very important indicator. If the extreme pressure and wear resistance performance is not good, it will lead to severe wear and tear of the equipment, causing equipment damage and equipment accidents.

There are four methods for measuring extreme pressure and wear resistance:

1 Timken test

This test is conducted on a Timken testing machine, where lubricating grease is applied at a certain flow rate between the friction pair of a metal ring and a metal block under a certain load and speed. After a certain period of operation, observe the wear marks on the metal block to determine the extreme pressure performance of the lubricating grease, expressed as an OK value.

1.1 Inspect the ability of lubricating grease to resist load under linear contact.

1.2 Test method: SH/T 0203

2. Four ball test (GB/T 3142)

The four ball test is to put lubricating grease into a ball box, and under a specified load, one steel ball above rotates at a certain speed against the three stationary steel balls below. Measure the wear diameter of the lubricating grease after a certain period of time to determine its extreme pressure performance.

This method has three representations: PB value, PD value, and ZMZ value

PB value: Refers to the maximum load under test conditions without jamming, expressed in N.

PD value: is the minimum load required to sinter a rotating ball with three stationary balls under experimental conditions, expressed in N.

ZMZ value: An index of the extreme pressure resistance of a lubricating grease under the applied load. During the test, the load is gradually added to three stationary steel balls at intervals of 0.1 logarithmic units, and the ZMZ value is calculated using the results of the first ten tests of sintering load, denoted by N.

3. Four ball test (GB/T12583) This method has three representation methods: PB value, PD value, and LWI value

LWI value: Refers to the extreme pressure capability index of the lubricant to minimize wear under the applied load. Under the conditions of this experiment, it is equal to the average value of the corrected load measured ten times by applying a load of 0.1 logarithmic units to three stationary spheres before burning the node.

4. Wear resistance (SH/T 0204)

On a four ball long grinding test machine, under specified load conditions, one steel ball above rotates against the three stationary steel balls below the surface coated with the sample. After the test is completed, the wear scar diameter of the three steel balls below is measured to determine the wear resistance of the lubricating grease based on the size of the wear scar diameter.

4.1 Significance: This method is used to determine the relative wear performance of different lubricating greases under experimental conditions, and cannot distinguish between extreme pressure and non extreme pressure lubricating greases.