Chemical vapor infiltration (CVI) is CVD with minor process changes that allow homogenous infiltration of porous structures such as foams and fiber preforms. Through control of pressure and/or thermal gradients within a reactor, gaseous precursors are allowed to uniformly permeate porous structures. Deposition of the desired compound thus occurs on all internal surfaces. CVI offers the ability to fabricate engineered porous structures such as reticulated foam from any of the materials that can be deposited via CVD.
Ultraviolet-activated chemical vapor deposition (UVCVD) is a variant of CVD that uses ultraviolet energy to drive the chemical reaction instead of thermal energy. The primary advantage of UVCVD is the ability to apply coatings at extremely low temperatures (room temperature to 300°C).