1. Types of coatings

We exclude layers obtained by thermal or thermochemical treatment.

• Electrolytic coatings: the layer created modifies the dimensions of the product. It grows outward from the surface of the product, and the presence of a clear interface allows for the use of all the methods described.

• Vacuum coatings: these are coatings obtained by vacuum evaporation of a pure metal (or alloy) or by cathodic sputtering. The layer created modifies the dimensions of the product and can be measured thanks to the existence of a clear interface.

• Chemical vapor deposition: the existence of an intermediate diffusion layer results in the absence of an interface and can cause measurement errors.

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