Polymeric fibers were produced from a polyaluminocarbosilane obtained by reacting polycarbosilane and an aluminum alkoxide modified with a beta-ceto ester. The pre-ceramic fibers were converted into amorphous Si-Al-O-N ceramic fibers after a pyrolysis process under flowing ammonia at 1000 C. 29Si and 27Al magic-angle spinning nuclear magnetic resonance investigations were performed to characterize the conversion process of the polymeric precursor fibers into the ceramic product. However, because of the amount ...
Polycarbosilane was modified by reaction with an aluminum alkoxide to get a precursor for Si-Al-C-O ceramics. The precursor was essentially characterized by magic-angle spinning nuclear magnetic resonance ((29)Si, (27) Al, and (13)C) and appeared as a dispersion of Al(OH)3-based particles in a polycarbosilane chain matrix. After the material was heat-treated under argon at 1500 C, X-ray diffraction showed that it crystallized mainly as SiC 2H. The presence of this rather ...
A polycarbosilane has been modified with aluminum alkoxide to obtain a new preceramic compound. The pyrolysis in NH3 flow of this polyaluminocarbosilane leads to the formation of an amorphous Si-Al-O-N phase. The nitridation process has been followed by IR and (29)Si MAS-NMR spectroscopies. A fine-grained beta'-SiAlON ceramic is obtained by firing the amorphous phase at 1500 C. The crystallization process has been studied by XRD, (29)Si MAS-NMR, and TEM techniques. ...
The synthetic utility of homogeneous titanium catalyzed redistribution of the cyclomers-(MeHSiO) (x)-(where x=4 or 5) and the linear oligomer -MeHSiO(x) - MeHSiO(x)-(M(n) approx. 2,200 D) was explored as a route to MeSiH3 and a methylsilsesquioxane-methylhydridopolysiloxane copolymer of approximate composition- MeHSiO 0.35 MeSi(O)1.5)0.65-. The high temperature behavior of the titantium derived methylsilsesquioxane copolymer follows closely that of similar polymers prepared by sol-gel processing. Heating under nitrogen to 800-1000 C at a ...
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