Alterungsverhalten silikonbasierter syntaktischer Schäume in Freiluftanwendungen

A next step in the development of silicone composite insulators is the partial substitution of cost-intensive silicone by cost-efficient fillers with low density. Therefore, hollow micro spheres (HMS) made of glass and ceramic are used and applied to liquid silicone rubber (LSR) and hightemperature vulcanized (HTV) silicone rubber. The new materials have to fulfill requirements for outdoor applications. To ensure this, extensive material ageing tests are performed. One focus is on examinations of hydrophobicity properties, especially the loss of hydrophobicity caused by electric discharges, UV-radiation, water, and acid. Another focus is on examinations of resistance against tracking, erosion, and arcing. Standardized test procedures are applied, whenever available. Since such test procedures are missing for examinations of hydrophobicity properties, recommended and published procedures are used instead. Chemical and physical examinations complete the analysis. Results show that the examined LSR is of limited suitability as matrix material for HMS, since cross-linking is disturbed. Promising results are achieved with the examined HTV. Hence, the usage of glass-HMS with surface treatment for improved chemical bonding between filler and matrix is recommended. This causes an increase of thermal stability compared to the commercially used reference material. Influence on hydrophobicity properties is negligible while specific material costs and density are reduced.