Progressive and constant load scratch testing of single- and multi-layered composite coatings

► Manufacturing of pigmented silicone-based multi-layer protective coatings.
► General properties of the multi-layer protective coatings.
► Influence of the scratch parameters on the deformation response of the coatings.
► Empirical model for evaluating the scratch response of the coatings.
► Chemical endurance of the coatings and analysis of the damage propagation.

The development of effective coating systems that offer high protection against erosion–corrosion is of utmost importance in several industrial sectors. Such a coating class is typically designed to provide an effective barrier against aggressive environments combined with cathodic protection. The adherence to the substrate ensures full performance and reliability of the coatings during service. In the present investigation, the scratch response of single- and multi-layered composite coatings made from superimposed layers of a modified phenyl–methyl silicone resin and of aluminum–magnesium (Al–Mg 4.5 wt%) metallic powders was investigated. The applied loads, the contact conditions between the indenter and coating surface and the sliding speeds were analyzed, and empirical models were developed accordingly. The scratch response of the composite coatings was mapped according to the testing conditions, thus providing a useful instrument for designers and practitioners.