ISO 20523:2017 specifies classification, designations and short names for carbon based films. These are films in which carbon is the predominant constituent part and which are deposited by physical vapour deposition (PVD) or chemical vapour deposition (CVD) process. This includes amorphous carbon-based films, also called diamond-like carbon films (DLC), as well as CVD diamond films, graphite and polymer-like films.

ISO 20523:2017 is applicable to those films which are produced on an industrial scale. Additional carbon based films are under development.

ISO 20523:2017 refers to the material of carbon based films. It does not refer to the entire coating that can consist of a main functional layer with additional layers below or on top.

A layer can change in composition and/or material property over its thickness. Such layers are called gradient layers. The definitions in this document refer to non-gradient layers.

A carbon based film can include other elements like hydrogen, metal elements or others. Metal constituents can be included as metal carbides. Films with additional elements are only covered by this document if carbon is the predominant constituent part. Carbon incorporated as carbide, as can be present in metal-containing amorphous carbon films (a-C:Me, a-C:H:Me), does not count to this amount.

ISO 20523:2017 does not apply to the class of carbon materials such as fullerenes, carbon nanotubes and graphene.