Preparation of silicon nitride by pyrolysis of iminopolysilanes

Technical Report · Mon Apr 01 04:00:00 EST 1985

OSTI ID:5789573

Hartvigsen, J J

Chlorination of CaSi/sub 2/ produces a chlorosilane mixture containing Si/sub 2/Cl/sub 6/ and Si/sub 3/Cl/sub 8/. These compounds may be separated by simple distillation. A reflux reactor system was developed in this work which has several advantages over the liquid ammonia process. The liquid ammonia layer in the Ube process is advocated as a means of removing NH/sub 4/Cl from the reaction product. However, material made in the reflux reactor, and subsequently washed with liquid ammonia, has the same chlorine content (100 ppM) after pyrolysis as the powder produced by Ube. There are potential advantages in using Si/sub 2/Cl/sub 6/ and Si/sub 3/Cl/sub 8/. The measured ceramic yields of Si/sub 2/(NH)/sub 3/ (88%) and Si/sub 3/(NH)/sub 4/ (94.6%) are higher than that of Si(NH)/sub 2/ (83%). Although none of the silicon imide compacts densified during pyrolysis at the relatively low temperatures (1200 to 1450/sup 0/C) which were used, the particles produced are sufficiently small (0.3 ..mu..m) that they might sinter at higher temperatures. Carbon may be incorporated into the silicon imide structure by copolymerizing a chlorosilane and a small amount of chloroalkane with ammonia. When such a powder was pyrolyzed, the resulting product was ..cap alpha.. - Si/sub 3/N/sub 4/ with no detectable SiC. The carbon in the powder was effective in reducing the oxygen content of the silicon nitride.

• Research Organization: Ames Lab., IA (USA)
• DOE Contract Number: W-7405-ENG-82
• OSTI ID: 5789573
• Report Number(s): IS-T-1159; ON: DE85012391
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360201* -- Ceramics
Cermets
& Refractories-- Preparation & Fabrication
CHEMICAL PREPARATION
CHEMICAL REACTIONS
DECOMPOSITION
HYDRIDES
HYDROGEN COMPOUNDS
IMIDES
NITRIDES
NITROGEN COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SILICON COMPOUNDS
PNICTIDES
PYROLYSIS
SILANES
SILICON COMPOUNDS
SILICON NITRIDES
SYNTHESIS
THERMOCHEMICAL PROCESSES