Thermal stability investigations of different aerogel insulation materials at elevated temperature

Abstract

Super thermal insulation materials with low thermal conductivities, such as aerogels and vacuum insulation panels, are increasingly pushing conventional thermal insulations out of the market. Super insulation materials such as aerogels can be used easily on both vehicles and buildings. Nowadays, their usage by pipes transporting hot medium is also widespread. In these environments where elevated temperatures (100–250 °C) are applied, it is a basic requirement that they should keep their excellent thermal insulating capability. In this study, a comprehensive examination performed on two new silica-aerogel type insulations is presented. We investigated the change in the thermal performance of different types of aerogel insulations (Slentex and Pyrogel) after thermal annealing, ageing them at 150 and 250 °C temperatures for 1 day. After these thermal treatments, their thermal parameters such as thermal conductivities and specific heat capacities were measured. We revealed that both the thermal conductivity and the specific heat capacity for the Pyrogel changed considerably after annealing, while for Slentex the thermal conductivity remained constant and the specific heat capacity changed. To understand these changes we executed calorimetry tests and microscopic inspections with different methods. These experiments were completed with X-ray diffractometry to analyze the possible structural changes in the samples. From an application point of view, we consider the importance of these results, since they predict the lifetime of the used insulating material during their industrial use.