Effect of HF and NaOH Etching on Chemical and Structure Stability of Hollow SiOC Ceramics.

Autor: Xia, Kedong, Zhang, Hui, Cheng, Yinfeng, Duan, Lingyao, Li, Yunling, Liu, Xiao
Zdroj: SILICON (1876990X); Apr2024, Vol. 16 Issue 5, p2171-2181, 11p
Abstrakt: The hollow SiOC ceramic microspheres were synthesized by using solvothermal method in NaHCO3 solution and followed by chemical etching with HF and NaOH solution. The oxygen-enriched unit of SiOC ceramics increases as increase of the pyrolysis temperature, and SiC nanowires are formed by carbothermal reduction reaction at 1400 °C. Although the C content increases after removing SiO2 by HF and NaOH solution, the etching effect of NaOH is inferior to that of HF etching. Independent of oxygen-rich units, SiOC ceramics with high graphitic C structure exhibit favorable structure and chemical durability. NaOH etching produces only mesopores and HF etching generates more micropores, both of which increases the specific surface area of SiOC ceramics as increase of pyrolysis temperature. Furthermore, HF etching results in the insertion of F element in SiOC ceramics and formation of F–Si bond. NaOH etching causes the residual Na element on surface of SiOC ceramics, which decreases the initial oxidation temperature of SiOC ceramics. The thermogravimetric analysis reveals that the oxidation resistance of SiC is superior to that of SiOC and C. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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