Chemical vapour infiltration of composites and their applications

This chapter focuses on chemical vapour infiltration (CVI). The CVI is considered an extension of the chemical vapour deposition (CVD) technology. In this latter technique, used for special coatings and electronic applications since 1960s, the coating is deposited from gaseous precursors at high temperatures on a completely dense solid surface. Fibres for Ceramic matrix composites (CMCs) should withstand the relatively high temperatures required to produce ceramics, without significant damage. Ceramic fibres, consisting of oxide or non-oxide fibres, are both suitable for CMCs. Fibre-reinforced CMCs, obtained by incorporating fibres in ceramic matrices, not only exploit their attractive high-temperature strength but also reduce the propensity for catastrophic failure. The CMCs with a continuous reinforcement consist of two classes: oxide matrix CMCs and non-oxide matrix CMCs. Fibre-reinforced CMCs and densification of such composites by a variety of infiltration routes is an open research area.