Elastic Properties of Silica Xerogels

Abstract

Longitudinal and transverse acoustic wave velocities have been measured for silica xerogels as a function of relative humidity in order to calculate elastic constants. The silica zerogels studied are microporous with open porosity of 53 vol %. The longitudinal wave velocity exhibits a minimum at about 35% RH (relative humidity). The transverse wave velocity decreases to a constant value for 35% and greater relative humidity. Consequently, Young's modulus is a minimum at 35% RH while the shear modulus decreases to a constant value at 35% RH. The bulk modulus and Poissons' ratio exhibit minimum values at about 15% RH. Young's modulus decreases from 4.91 GPa to 3.42 GPa at 35% RH and then increases to 3.60 GPa at 55% RH. Poisson's ratio decreases from 0.184 to 0. 164 at 15% RH and then increases to 0.272 at 55% RH. Below 35% RH, silica xerogels adsorb a monolayer of hydroxyls while above 35% RH silica xerogels show pore filling. (aw)

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Document Details

Document Type
Technical Report
Publication Date
Jan 03, 1990
Accession Number
ADA216528

Entities

People

  • Bennet Abramoff
  • Lisa C. Klein

Organizations

  • Rutgers University–New Brunswick

Tags

Communities of Interest

  • Weapons Technologies

DTIC Thesaurus Topics

  • Acoustic Waves
  • Adsorption
  • Body Weight
  • Bulk Modulus
  • Elastic Properties
  • Materials
  • Mechanical Properties
  • Military Research
  • Modulus Of Elasticity
  • New Jersey
  • Numbers
  • Security
  • Shear Modulus
  • Silicon Compounds
  • Transverse Waves
  • United States
  • Universities

Fields of Study

  • Materials science

Readers

  • Electrochemical Engineering/ Fuel Cell Technologies
  • Mathematics or Statistics
  • Mechanical Engineering/Mechanics of Materials.