Silicone oil applications in the lubrication industry originally have these unique properties

December 24, 2023

Silicone oil applications in the lubrication industry originally have these unique properties

01 What is silicone oil

Silicone oil is also known as polysiloxane, and its silicon-oxygen bond is very stable, so silicone oil has good thermal stability and oxidation stability. At present, the silicone oils used as lubricating oil mainly include methyl silicone oil, methyl phenyl silicone oil, methyl chlorophenyl silicone oil and ethyl silicone oil.

Methyl silicone oil is generally used as damping fluid and special purpose grease Base Oil; Ethyl silicone oil is mainly used for precision instrument oil; Methyl phenyl silicone oil is often used in the production of synthetic high temperature grease base oil because of its high temperature resistance, low freezing point and good oxidation resistance. Chloro-silicone oil has better lubricity than other silicone oils, so it is often used as a base oil for preparing medium-load greases.

02 Application of silicone oil in lubrication
1. Antifoaming agent/antifoaming agent for lubricating oil

The lubricating oil in the lubricating oil system is usually a forced circulation operation mode, and some air is often entered in the operation, which will produce bubbles and bubbles in the case of fierce agitation, and the larger air bubbles can quickly rise to the surface of the oil, while the smaller bubbles rise slowly. No matter in which form it exists in the oil, it will have an adverse effect on the equipment, which may make the oil pressure of the oil pump go up and affect the oil circulation, destroy the oil film, wear, and the oil pressure is unstable, affecting the adjustment, and the foam spills from the top of the fuel tank and threatens the operation of the unit, so the oil must have anti-foam performance.

In order to eliminate the foam produced by the working medium in the equipment system, after long-term observation and research, a variety of defoaming methods have been found, such as physical defoaming method, mechanical defoaming method, chemical defoaming method, etc. The chemical defoaming method has the best effect and is simple, so it is widely used at home and abroad.

Methylsilicone oil as an antifoam agent is related to its following properties:

(1) The surface tension is lower than the lubricating oil, which promotes the desorption of the blowing agent, but the surface film strength formed by it is poor;

② It has a small solubility in lubricating oil, but it has a certain lipophilicity;

③ Chemical properties are not active, not easy to react with lubricating oil;

④ Low dosage, good effect, even at high temperature can effectively eliminate the foam in the lubricating oil;

⑤ Methyl silicone oil has the advantages of low volatility, good viscosity and temperature, high flash point, low freezing point, good thermal stability and long service life. The commonly used viscosity of dimethylsilicone oil that plays the role of antifoaming in lubricating oil is (25℃ kinematic viscosity) 100-100000cs, and the amount of use is 5-50mg/kg.

2. Application of silicone oil in precision instrument lubrication

Precision instrument oil is a low temperature resistant instrument oil which is composed of low viscosity synthetic lubricating oil with excellent viscosity and temperature, and is prepared with many additives such as anti-oxidation and anti-rust. This precision instrument oil is designed for low temperature and low torque of precision instruments and timers, high precision micro bearings, gear shaft and slide shaft lifelong lubrication, with excellent oxidation resistance, anti-wear and low temperature properties.

Silicone oil is the base oil commonly used in precision instrument lubricating oil. The silicone oxygen bond energy in silicone oil is as high as 1014.2kJ/mol, which makes silicone oil have excellent thermal stability and oxidation resistance, which can ensure that the decomposition reaction is not easy to occur under high temperature conditions, so as to avoid damage to the quality of oil. At the same time, silicone oil also has excellent low temperature resistance, and the pour point can be lower than -50℃.

The viscosity and temperature performance of silicone oil is smaller than that of mineral oil, and the viscosity changes little with the temperature, so that the same lubrication performance is maintained in the case of little temperature change, ensuring the accurate operation of precision instruments. The stable chemical properties of silicone oil also give it good rust resistance, protect precision internal parts from corrosion, and the shelf life of silicone oil is very long, precision instruments use silicone oil as lubricating oil can be used for a long time, reduce the number of replacement.

3. Application of silicone oil in vibration reduction
Silicone oil is a liquid polyorganosiloxane, with excellent high and low temperature resistance, chemical stability, shear resistance, viscosity and temperature characteristics and high compression rate. Vibration reduction products based on silicone oil are widely used in electronic and electrical equipment, tall buildings, Bridges and weapon platforms.

The viscosity temperature coefficient of silicone oil is lower than that of organic polymer with carbon chain structure, which is mainly due to the large bond Angle and bond energy, large degree of freedom of orientation and good flexibility of silicone oil molecular chain. In all kinds of silicone oil, the temperature viscosity coefficient of methyl silicone oil is the smallest, and its viscosity changes with the temperature is the least, so it is most suitable for the base oil of damping liquid.

With the increase of temperature, the viscosity of methyl silicone oil changes greatly in the low temperature section, but it changes less and less in the high temperature section. Therefore, methyl silicone oil is suitable for the use of damping materials at higher temperatures. The damping performance of silicone oil based damping liquid is stable over a wide range of temperature and frequency. However, in order to further improve the damping performance of silicone oil, it is often necessary to add a certain amount of filler to increase viscosity.

In fact, because the molar mass of general methicone has a certain distribution, it is polydispersed, which indicates that the viscosity temperature coefficient is also related to the distribution of molar mass, and the required viscosity methicone with a lower viscosity temperature coefficient can be prepared with different viscosity methicone as the base oil of the damping liquid. The common viscosity (kinematic viscosity at 25℃) of dimethylsilicone oil used as damping liquid is 1000-10000cs.

Author:

Mr. James

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sales@cn-lubricantadditive.com

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