1. Coating types

We exclude coatings obtained by thermal or thermochemical treatment.

• Electrolytic coatings: the layer created changes the dimensions of the product. It grows from the product surface outwards, and the presence of a clean interface means that all the methods described can be used.

• Vacuum deposits: these are deposits obtained by vacuum evaporation of a pure metal (or alloy) or by sputtering. The layer created alters the dimensions of the product, and is measurable thanks to the existence of a clean interface.

• Chemical deposits in the gas phase: the existence of an intermediate diffusion layer results in the absence of an interface, and can lead to measurement errors.

• Conversion...