Focused Ion Beam-Prepared Transmission Electron Microscopy Examination of Atmospheric Chemical Vapor-Infiltrated Silicon Carbide Morphology.

Silicon carbide (SiC)-based ceramic matrix composites (CMCs) are utilized for their refractory properties in the aerospace industry. The composition and structure of these materials are crucial to maintaining the strength, toughness, oxidation, and creep resistances that are desired of silicon carbide. This work analyzes the chemical composition of the matrix in batches of SiC/SiC (silicon carbide fiber-reinforced silicon carbide matrix) minicomposites that are processed by chemical vapor infiltration of the BN interphase and SiC matrix on single Hi-Nicalon Type S fiber tows using a range of processing parameters.

Morphological Control of Silicon Carbide Deposited on Hi-Nicalon Type S Fiber Using Atmospheric Pressure Chemical Vapor Infiltration.

Silicon carbide coated onto Hi-Nicalon Type S fiber is of great interest to the aerospace industry. This work focuses on tuning the reaction parameters of atmospheric pressure SiC CVI using CHSiCl to control the morphology of the coatings produced. Depth of CHSiCl from 1 to 14 cm, temperature from 1000 to 1100 °C, and flow rate of H carrier gas from 5 to 30 SCCM were examined.

Rapid Chemical Vapor Infiltration of Silicon Carbide Minicomposites at Atmospheric Pressure.

The chemical vapor infiltration technique is one of the most popular for the fabrication of the matrix portion of a ceramic matrix composite. This work focuses on tailoring an atmospheric pressure deposition of silicon carbide onto carbon fiber tows using the methyltrichlorosilane (CHSiCl) and H deposition system at atmospheric pressure to create minicomposites faster than low pressure systems. Adjustment of the flow rate of H bubbled through CHSiCl will improve the uniformity of the deposition as well as infiltrate the substrate more completely as the flow rate is decreased.