TY  - JOUR
AU  - Simonenko, E. P.
AU  - Simonenko, N. P.
AU  - Kopitsa, G. P.
AU  - Pipich, Vitaliy
AU  - Sevastyanov, V. G.
AU  - Kuznetsov, N. T.
TI  - How xerogel carbonization conditions affect the reactivity of highly disperse SiO2–C composites in the sol–gel synthesis of nanocrystalline silicon carbide
JO  - Russian journal of inorganic chemistry
VL  - 61
IS  - 11
SN  - 1531-8613
CY  - Moscow
PB  - MAIK Nauka/Interperiodica Publ.
M1  - FZJ-2016-07670
SP  - 1347 - 1360
PY  - 2016
AB  - A transparent silicon polymer gel was prepared by sol–gel technology to serve as the base in the preparation of highly disperse SiO2–C composites at various temperatures (400, 600, 800, and 1000°C) and various exposure times (1, 3, and 6 h) via pyrolysis under a dynamic vacuum (at residual pressures of ~1 × 10–1 to 1 × 10–2 mmHg). These composites were X-ray amorphous; their thermal behavior in flowing air in the range 20–1200°C was studied. The encapsulation of nascent carbon, which kept it from oxidizing in air and reduced the reactivity of the system in SiC synthesis, was enhanced as the carbonization temperature and exposure time increased. How xerogel carbonization conditions affect the micro- and mesostructure of the xerogel was studied by ultra-small-angle neutron scattering (USANS). Both the carbonization temperature and the exposure time were found to considerably influence structure formation in highly disperse SiO2–C composites. Dynamic DSC/DTA/TG experiments in an inert gas flow showed that the increasing xerogel pyrolysis temperatures significantly reduced silicon carbide yields upon subsequent heating of SiO2–C sys- tems to 1500°C, from 35–39 (400°C) to 10–21% (1000°C).
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000388704300002
DO  - DOI:10.1134/S0036023616110206
UR  - https://juser.fz-juelich.de/record/825199
ER  -