Mechanical Properties and Brittle Behavior of Silica Aerogels

Gels

Juan Primera¹  Adil Alaoui²  Thierry Woignier³  Sylvie Calas-Etienne⁴  Pascal Etienne⁴  Florence Despestis⁴ 

[1] Departamento de Fisica, FEC, LUZ, 4011 Maracaibo, Venezuela;Faculté des Sciences et Techniques de Tanger, B.P. 416, 90000 Tanger, Marroco;Institut Méditerranéen de Biodiversité et d’Ecologie marine et continentale (IMBE), Aix Marseille Université, CNRS, IRD, Avignon Université, UMR CNRS 7263, 13397 Marseille, France;Laboratoire Charles Coulomb, Université Montpellier 2, Place E. Bataillon, 34095 Montpellier Cedex 5, France;

关键词: aerogels;    porous glasses;    mechanical properties;    elastic properties;    toughness;    weibull statistic;    stress corrosion effect;   

DOI  :  10.3390/gels1020256

来源: DOAJ

【 摘 要 】

Sets of silica gels: aerogels, xerogels and sintered aerogels, have been studied in the objective to understand the mechanical behavior of these highly porous solids. The mechanical behaviour of gels is described in terms of elastic and brittle materials, like glasses or ceramics. The magnitude of the elastic and rupture modulus is several orders of magnitude lower compared to dense glass. The mechanical behaviours (elastic and brittle) are related to the same kinds of gel characteristics: pore volume, silanol content and pore size. Elastic modulus depends strongly on the volume fraction of pores and on the condensation reaction between silanols. Concerning the brittleness features: rupture modulus and toughness, it is shown that pores size plays an important role. Pores can be considered as flaws in the terms of fracture mechanics and the flaw size is related to the pore size. Weibull’s theory is used to show the statistical nature of flaw. Moreover, stress corrosion behaviour is studied as a function of environmental conditions (water and alcoholic atmosphere) and temperature.

【 授权许可】

Unknown