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Pyrolytic Conversion of Spherical Organo‐silica Powder to Silicon Nitride under Nitrogen
Author(s) -
Choi Jae Young,
Moon Young Tae,
Kim Do Kyung,
Kim Chong Hee,
Seog InSig
Publication year - 1998
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1998.tb02624.x
Subject(s) - materials science , pyrolysis , pyrolytic carbon , nitrogen , carbon fibers , dispersity , chemical engineering , silicon , silicon nitride , particle size , particle (ecology) , biogenic silica , composite number , organic chemistry , chemistry , composite material , polymer chemistry , metallurgy , oceanography , engineering , geology , botany , biology , diatom
Monodisperse, spherical Si 3 N 4 powder composed of fine particulates was synthesized by pyrolyzing spherical organo‐silica powder under nitrogen. The organo‐silica powder was prepared by hydrolyzing a mixture of phenyltrimethoxysilane (PTMS) and tetraethoxysilane (TEOS) in a methanol solution of water and ammonia. The organo‐silica powder consisted of 81.3 at.% silicon units derived from PTMS and 18.7 at.% silicon units derived from TEOS. During the pyrolysis under nitrogen, the organo‐silica powder decomposed to a mixture of free carbon and silica, with an increase of the surface area, at 500°‐600°C, followed by the formation of alpha‐Si 3 N 4 , with ß‐Si 3 N 4 as a minor phase, at 1450° and 1500°C and ß‐SiC at 1550°C. The pyrolyzed powders, which retained the spherical shape and monodispersity of the organo‐silica powders, with a reduction in mean particle diameter, were composed of fine particulates that were ~40 nm in size.