Published 1986
| Version v1
Report
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Study of the silica aerogel densifications by SAXS and BET
- 1. Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)
- 2. Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica e Quimica
- 3. Monpellier Univ. (France). Lab. de Sciences de Materiaux Vitreux
Description
Silica gels were made by hydrolysis and polycondensation of solutions containing tetramethoxysilane (TMOS), methanol and water in a neutral medium. After hypercritical drying, the aerogels were densified at high temperatures (10800C). The obtained porous materials have apparent densities between 0,71 and 2,20 g/cm3 and specific surfaces, measured by BET, below 295 m2/g. The structural evolution of the porous material was studied by small-angle X-ray scattering (SAXS). There are two competitive mechanisms that contribute to Densification: the elimination and coalescence of mesopores, and the progressive densification of the nearly homogeneous vitreous matrix. (author)
Availability note (English)
MF available from INIS under the Report Number.Abstract (Portuguese)
Geis de silica foram produzidos por hidrolise e policondensacao de solucoes de tetrametoxisilano (TMOS), metanol e agua em meio neutro. Apos secagem hipercritica, os aerogeis foram submetidos a um processo de densificacao a altas temperaturas (10800C). Os materiais porosos obtidos tem densidade variando de 0,71 a 2,20 g/cm3 e superficie especifica medida por BET de ate 295 m2/g. A evolucao estrutural do material poroso foi estudada pela tecnica de espalhamento de raios-x a baixo angulo (SAXIS). Concluiu-se que contribuiram na densificacao dois mecanismos competitivos: a eliminacao e coalescencia de mesoporos e a densificacao progressiva da matriz vitrea quase homogenea. (autor)Files
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Additional details
Additional titles
- Original title (Portuguese)
- Estudo da densificacao de aerogeis de silica por SAXS e BET
Publishing Information
- Imprint Pagination
- 16 p.
- Report number
- CBPF-NF--043/86
INIS
- Country of Publication
- Brazil
- Country of Input or Organization
- Brazil
- INIS RN
- 21078422
- Subject category
- S36: MATERIALS SCIENCE; S36: MATERIALS SCIENCE;
- Descriptors DEI
- ADSORPTION; COALESCENCE; DENSITY; NITROGEN; POROUS MATERIALS; SILICA GEL; SMALL ANGLE SCATTERING; SOL-GEL PROCESS; VERY HIGH TEMPERATURE; X RADIATION
- Descriptors DEC
- ADSORBENTS; ELECTROMAGNETIC RADIATION; ELEMENTS; IONIZING RADIATIONS; MATERIALS; NONMETALS; PHYSICAL PROPERTIES; RADIATIONS; SCATTERING