The term CVD covers a group of processes that deposit a solid material from a gas phase onto a target substrate. At ambient temperature or just above and usually diluted in a carrier gas, the precursor gases are introduced into the reaction chamber where they come into contact with a heated substrate and either decompose or react. The substrate temperature will influence the outcome of the reaction or decomposition processes that take place at the substrate surface. CVD is a versatile technique that can be used to coat both ceramic and metallic layers or produce bulk materials.
CVI is a derivative of CVD enabling the infiltration where material is deposited within the bulk of a porous structure. For example, the infiltration of fibre performs to produce ceramic matrix composites such as C-C, C-SiC and SiC-SiC with enhanced oxidation resistance.