Microwave Heated Chemical Vapor Infiltration: Densification Mechanism of SiCf/SiC Composites
Abstract:Silicon carbide fiber-reinforced silicon carbide matrix composites (SiCf/SiC) have been produced using microwave heated chemical vapor infiltration. Preferential densification of the composite from the inside out was clearly observed. Although an average relative density of only 55% was achieved in 24 h, representative of an ∼26% increase over the initial fiber vol%, the center of the preform densified to 73% of the theoretical. The densification mechanisms were investigated using X-ray absorptiometry and scanning electron microscopy. The initial inverse temperature profile obtained, which was found to result in the efficient filling of the intratow porosity, although not the intertow porosity, flattened out after approximately 6 h as the densification front moved outward toward the edges. Although not investigated directly, the evidence suggested that this was caused by changes in both the thermal conductivity and microwave absorption characteristics as the samples densified.
Document Type: Research Article
Affiliations: 1: Institute of Polymer Technology and Materials Engineering, University of Loughborough, Loughborough LE11 3TU, UK 2: QinetiQ Ltd., Cody Technology Park, Farnborough GU14 0LX, UK 3: Division Materials, School of Mechanical, Materials, Manufacturing Engineering and Management, University of Nottingham NG7 2RD, UK
Publication date: September 1, 2006