Instrumented Indentation of Super-Insulating Silica Compacts

Abstract

Highly porous silica compacts for superinsulation were characterized by instrumented indentation. Samples showed a multi-scale stacking of silica particles with a total porous fraction of 90 vol %. The two main sources of silica available for the superinsulation market were considered: fumed silica and precipitated silica. The compacts processed with these two silica displayed different mechanical properties at a similar porosity fraction, thus leading to different usage properties, as the superinsulation market requires sufficient mechanical properties at the lowest density. The measurement of Young’s modulus and hardness was possible with spherical indentation, which is an efficient method for characterizing highly porous structures. Comparison of the mechanical parameters measured on silica compacts and silica aerogels available from the literature was made. Differences in mechanical properties between fumed and precipitated compacts were explained by structural organization.

Characteristics of Insulating Panels Realised from Coconut Palm Fibres for Low-Temperature Thermal Insulation

“…Insulating panels are expensive, however, and are still confined to high added-value applications. If they are to be used more widely in the building sector, the total cost of the raw materials used in their manufacture will have to be reduced [8]. The materials commonly used are synthetic, such as polyurethane, polystyrene, polyvinyl chloride, fillers for fabrics and mineral fibres such as rock wool and glass fibre [9,10].…”

Brittle Materials in Mechanical Extremes

“…Several techniques have been used in the literature (and were used in this Special Issue) to characterize this behavior: instrumented indentation (see, for instance, the book of Buljak [ 9 ], or the contribution [ 10 ] to this Special Issue) is particularly suitable to monitor the variation of the Young’s modulus as a function of the load, thereby allowing insights into “mechanical microcracking” (see [ 11 ] for its definition). Moreover, indentation allows for the use of inverse methods to extract the (non-linear) constitutive behavior of materials [ 12 ].…”