BN and SiBN Fiber Coatings Via Cvd Using a Single Source, Liquid Precursor Based on Borazine

Abstract

Borazine (B3N3H6) is a liquid, high vapor pressure chemical useful for depositing BN and Si-doped BN coatings via chemical vapor deposition (CVD). Due to lower cost and high experience factors, BCl3 has been the favored precursor for coatings containing B and N in spite of hazards associated with its handling and effluent abatement. Silane or disilane gases, which are moderately or highly pyrophoric, are typically used to provide Si to CVD Si doped BN (SiBN). Borazine's attractiveness is increasing due to a new synthesis route with potential cost reductions, the ability to provide B and N in a single liquid CVD precursor, and the potential for adding dopants using a neat liquid source. Borazine is compared with BCl3 using a variety of parameters which emphasize its potential as a BN precursor. BN and SiBN coatings deposited from borazine on Hi-Nicalon were characterized in the as-deposited condition and following heat treatment under an argon atmosphere using scanning and transmission electron microscopy, energy dispersive x-ray analysis and Auger spectroscopy.