CVD – Chemical Vapour Deposition
CVD is a high temperature process (usually > 900ºC) which uses a gas phase chemical reaction to form a coating. CVD is excellent for producing high temperature materials such as nitrides, carbides and oxides either as adherent coatings or free-standing shapes by releasing the coating from its substrates.
CVI – Chemical Vapour Infiltration

CVI is a form of CVD where the process conditions are adjusted so that coating is formed over the surface of every individuals fibre in a porous fibre bundle structure or preform. Over a long period of processing most of the porosity in a fibre structure can be filled up producing a high-density ceramic matrix composite (CMC). Matrix materials are typically Silicon Carbide or Carbon.
ATL CVI units typically use cold-wall reactors because these make larger working diameters possible. ATL CVI units are fully automatic because of the very long process times. Pumping systems are normally supplied in a corrosion resistant version with exhaust gas neutralisation.
PACVD – Plasma Assisted Chemical Vapour Deposition

PACVD uses electrical excitation of the active gas in a CVD reactor to produce coatings at much lower temperatures than would be required for conventional CVD. This makes possible the coating of heat sensitive substrates such as hardened steels and electronic materials. PACVD also makes possible the deposition of non-equilibrium materials such as diamond like carbon.
MOCVD – Metal Organic Chemical Vapour Deposition
MOCVD has been developed to provide coatings, particularly epitaxial layers at much lower temperatures than CVD. This is achieved by using specially volatile organometallic precursors that decompose at low temperature (<500ºC).