Dimethyl silicone oil and methyl phenyl silicone oil are widely used in hydraulic transmission systems and liquid connectors due to their wide viscosity range of 50 to 500,000 mm²/s. Compared to other liquids, silicone oil exhibits superior heat resistance and oxidation resistance, as well as a broader temperature-viscosity characteristic. In order to maintain viscosity and torque stability under extreme high temperature conditions, such as 100°C to 200°C, and prevent gel formation, a suitable amount of carbon-containing diimide compound can be added to the silicone oil as a viscosity and torque stabilizing additive to meet the hydraulic transmission requirements under harsh conditions.

The mechanism and effect evaluation of additives
The recommended dosage of the additive is 0.1% to 3.0% of the silicone oil mass, and it can be used in combination with other amine and phenolic antioxidants. The addition of carbodiimide compounds can capture acidic substances that may be produced by silicone oil at high temperatures, thereby preventing the degradation of the silicon-oxygen bond due to acid catalysis. This mechanism significantly enhances the thermal stability of silicone oil.

Performance Evaluation Example
Taking dimethyl silicone oil with a viscosity of 10000 mm²/s as an example, it is modified by adding 2.0% N, N1-dicyclohexylcarbodiimide by mass fraction. The viscosity stability of the modified silicone oil is evaluated by the following method: first, adjust the water content in the silicone oil to 600 ppm, and then seal it in a pressurized container. After heating at 170°C for 96 hours, measure the kinematic viscosity of the silicone oil and calculate the viscosity change rate. A low value of viscosity change rate indicates that the silicone oil has better thermal stability. Under specific test conditions, the silicone oil with N, N1-dicyclohexylcarbodiimide added shows a viscosity change rate of -0.3%, while the viscosity change rate of the silicone oil without this compound under the same conditions is -6.9%. This comparison highlights the significant improvement effect of additives on the thermal stability of silicone oil.