In World War II, silicone oil had a huge influence in the war. When Germany invaded the former Soviet Union, it was experiencing a severe winter that was once in a hundred years. The oil inside the machinery was frozen, and all tanks and armored equipment of the mechanized forces of Fascist Germany and the former Soviet combat forces could not be used. Faced with this harsh situation, scientists in the former Soviet Union discovered that a substance mixed with oil can prevent freezing. This substance is the silicone oil we know today. It is said that it is precisely because of silicone oil that the former Soviet Union gained a great advantage, defeated the German fascism, and made important contributions to the world's anti-fascist war.

Because of their special characteristics, military installations and military equipment are often made of materials with excellent properties, and silicone oil is just one of these excellent properties. Silicone oil is often used for these kinds of purposes in the military:

1. Instrument oil
Using silicone oil as instrument oil has the characteristics of long service life, good oxidation stability, low volatility and use in a wide temperature range. Our country has three series of silicone oil instrument oil products: -60-120℃, -60-150℃ and -60-200℃, which are widely used in precision instrument bearings, various aviation timing instruments, miniature motor bearings and various instruments. lubricating.

2. Specific liquid
In the automatic control system of modern aircraft, a large number of liquid floating gyroscopes, floating accelerometers, magnetic compasses, sensors, etc. are used. Most of them use liquid suspension to reduce bearing load and friction torque, and improve sensitivity, accuracy and stability. The liquid used is required to have a specific viscosity and density, good viscosity-temperature performance and low freezing point. Representative silicon oil special liquids include No. 4118 gyro oil, No. 4119 damping oil, No. 4120 sensor oil and No. 4126 gyro instrument oil.

3. Hydraulic oil
The U.S. Air Force divides hydraulic oil into six categories according to the operating temperature range of the hydraulic system. The operating temperatures of the third and fourth categories are -54-204°C and -54-288°C, respectively. Silicone oil and silicate are most likely to meet these two categories. Specification of oil-like oil. American Oronite 8200, 8515, 70 and other products based on hexa-(2-ethylbutoxy) disiloxane meet the MIL-H-8446 synthetic hydraulic oil specification. The hydraulic oils such as OS-45 and OS-45-1 in the United States, FH-4 and FH-8 in France, and my country's 4601, 4602 aviation hydraulic oil are also such products, but the working temperature is -54-175℃. Methyl chlorophenyl silicone oil is also used as hydraulic oil for aircraft, such as F-50, DP-47, MS-6 in the United States, and BT-301 in the former Soviet Union.

4. Damping fluid
High-viscosity silicone oil can be used as a shock-absorbing fluid for torsional vibrations transmitted from crankshafts of diesel engines, automobiles, tanks, etc.; it can also be used to reduce the pointers of instruments and instruments that have severe vibrations on aircraft, automobiles, motorcycles, ships and various industrial installations. Swing fluid makes the meter display correct instructions when vibrated severely; at the same time, it can also be used as a buffer tank, shock absorber and other dampers. The methyl chlorophenyl silicone oil at room temperature of 300mm2/s can be used as the shock absorber of the rotary vane hydraulic shock absorber of the tank, and used for the action cylinder of the spacecraft transmission device. Methyl silicone oil and methyl phenyl silicone oil can be used as the working fluid of the liquid timer of the spacecraft, the shock absorber of the shock absorber of the spacecraft structure, the shock absorber for the submarine launching missile, and the liquid spring of the soft landing support frame of the spacecraft. The shock absorber of vehicles, especially tanks, is increasingly using oil-gas suspension devices to replace leaf spring shock absorbers. The shock absorber used must have excellent viscosity-temperature performance, low-temperature fluidity, shear stability and rubber adaptability. , And the mixed oil of silicone oil and mineral oil can fully meet this requirement after adding a variety of additives.

5. Brake fluid
Silicone oil has good hydrophobicity, chemical inertness and electrical insulation, and is suitable for automobile brake fluid. The standard of silicone oil brake fluid is MIL-B-4617A, FMVSS　NO116 of DOT5, SAEJ1705 and China’s GB10830　JG5. This kind of brake fluid is used in some military vehicles, tanks, and postal vehicles. Compared with alcohol ether type brake fluids, silicone oil brake fluids have the following characteristics: Silicone oil has low hygroscopicity, and its boiling point and viscosity hardly change after moisture absorption; it is compatible with all metal and non-metal materials of the brake system. It will not cause electrochemical corrosion; the braking system is stable, even at a high temperature of 250 ℃ and a low temperature of -40 ℃, in dry heat or humid environment, it can operate safely.

6. Heat transfer oil
Silicone oil with lower viscosity is a good heat transfer medium. Methyl silicone oil, methyl phenyl silicone oil and methyl phenyl ether-based silicone oil can conduct heat transfer in the range of 100-300 ℃. Adding a small amount of thermal oxidation stabilizer can also make The working temperature is higher. Methyl silicone oil and methyl phenyl silicone oil with a viscosity of about 150mm2/s (20°C) can be used as the heat transfer medium of the oil bath to measure the high temperature viscosity of the fluid, instead of measuring the melting point of the substance in the sulfuric acid bath. Silicone oil is non-corrosive, does not change color, and can remain clear and transparent, which is convenient for observation. Silicone oil, as a heat transfer oil used in industry, has more and more applications. Ethyl silicone oil with a viscosity of 200mm2/s (20°C) can be used as a heat transfer medium in the jacket of the enamel reactor and used continuously below 180°C. The viscosity and acid value will basically remain unchanged after two years. Silicone oil with a medium phenyl content is used as a heat transfer oil in oil production equipment operating downhole. Tetraaryl silicate or alkyl aryl silicate adds a small amount of heat-resistant aromatic compounds or quaternary amines to resist hydrolysis and antioxidants, and can be made into heat transfer oil that can be used up to 380°C. The heat transfer oil used as a solar heating device is methyl silicone oil with additives. It has the characteristics of low vapor pressure, non-freezing at low temperature, and non-volatile at high temperature. It can work stably for a long time when the maximum temperature of the solar collector is below 200°C.

7. Electrical insulating oil
Silicone oil is suitable for insulating cooling oil, buffer oil, transformer oil, insulating immersion oil and heat dissipation oil. After the 1970s, silicone oil has made some breakthroughs as electrical oil. Silicone oil transformer oil can work above 175°C for a long time, allowing a temperature rise of 115°C when the transformer is working (generally only 65°C for mineral transformer oil), thus reducing the volume of the transformer, and it is safe and reliable in operation, with low flammability, even Burning can also produce silica and self-extinguish, eliminating the need for firewalls and fire protection facilities when using mineral transformer oil. Silicone oil can be used in small transformers in aviation and radio; as filler and dielectric fluid in semiconductor and silicon rectifier components, it is beneficial to improve the reliability and stability of components and extend the service life of components. In particular, methyl cyanosilicone oil, with a dielectric constant of up to 40, is more suitable as a dielectric fluid for the electrical and electronic industry, especially for ultra-small capacitors.

Low-viscosity methyl phenyl silicone oil has been used as the insulating dipping liquid for large power capacitors and has achieved satisfactory results. Porcelain bottle insulators in substations and transmission lines are coated with silicone oil or grease with a viscosity of 3000-5000mm2/s at 25°C, which can eliminate the influence of rain, moisture and dust, and operate safely for 4-5 years.

Low viscosity methyl silicone oil, ethyl silicone oil, low phenyl methyl silicone oil can also be mixed with insulating oils such as dodecylbenzene and carbon tetrachloride in a certain proportion to make transformers, capacitors, rectifiers, electromagnetic switches, Flame-resistant insulating oil for conveyors, etc.

8. Silicone rubber
The difference between ordinary silicone rubber made of silicone oil is that: silicone rubber has a larger temperature working range, ordinary silicone rubber can work between -40°C and 180°C, and special silicone rubber can withstand high temperatures of 300°C and- Low temperature of 70℃. In addition to resistance to high and low temperature, silicone rubber is resistant to radiation, water repellency, insulation, and other properties. Silicone rubber is often used as a sealing strip and some parts that are resistant to high and low temperature and radiation in military equipment.