Effect of combined UV thermal and hydrolytic aging on micro-contact properties of silicone elastomer

Silicone elastomer seals are widely used in aerospace field due to the unique performance. However, aging and degradation problems still exist under the harsh working environment, such as ultraviolet radiation and high-low temperature. In this paper, combined UV thermal and hydrolytic aging tests have been carried out and the aging mechanism of silicone elastomer is studied by Nicolet 380 ATR-FTIR instrument. Then, fractal surface model of silicone elastomer seal is developed based on the surface topography, which is measured by optical digital microscope. Finally, finite element contact model of the fractal surface is developed to analyze the coupling aging effects on micro-contact characteristics of silicone elastomer. Results indicate that compression set and hardness of silicone elastomer increases when aging time increases; combined UV thermal and hydrolytic aging may lead to the increasement of hardness; contact pressure increases and the contact area decreases in the aging process. Finite element model based on fractal theory provides an effective method to study the micro-contact properties of rubber sealing.