Vitreous enamels represent a class of coatings with different technological properties, mainly appreciated for the protection they guarantee to the covered substrates. This review introduces enamel coatings, describing their production technologies and presenting the main properties affecting the enamel’s durability. Firstly, this review article introduces the most important studies regarding the improvement in abrasion resistance, highlighting both successes and failures. Afterward, the work reveals an outlook about the resistance to chemicals, underlining the good resistance of enamels toward acidic chemicals and discussing the results of studies aimed to improve their performances toward alkaline solutions. This review also considers the corrosion protection property of enamels, highlighting the high barrier effect they provide against the absorption of aggressive substances toward metal substrates. Finally, new perspectives and possible future research paths are presented, being aware that this kind of coating offers both good product protection and functional integrity over time.

Porcelain enamel is an inorganic-type coating, which is applied to metals or glass for both decorative and functional purposes. This coating is a silica-based solidified glass mass obtained by high-temperature firing (temperature can range between 450 and 1200 °C depending on the substrate). Porcelain enamel coatings differ from ceramic coatings mainly by their glass structure and dilatation coefficient, and from organic paints mainly by the inorganic nature of the matrix and the chemical bond that exists between the coating and the substrate.

Powder coatings are commonly used to protect metallic substrates because of their good protection properties together with their aesthetical ones. In this work, the aesthetic and functional properties of powder coatings admixed with pearlescent pigments were investigated. The main aim of this work is represented by the evaluation of the coating properties and their change assessment after accelerated ageing treatments, such as UV and salt spray exposure. Changes in gloss, color and roughness were recorded before, during, and after UVA and UVB exposure. All the samples showed good resistance to UVA irradiation, whereas UVB light caused a huge variation in surface properties. Further insights on the degradation of the polymeric matrix were gained by exploiting FT-IR analyses, which could be correlated to the change of color. The protection properties of the coating were assessed by exploiting an acetic salt spray test. All the samples showed good resistance to aggressive environments, and no pigment effect on the degradation of the coatings could be detected.

Our study will be focused on stainless steel AISI 304—carbon steel ASTM A105 joints obtained by rotary friction welding and on their fatigue corrosion behavior in different testing environments. As a first thing, the joints will be characterized by microscopy and electrochemical techniques. The manuscript will then describe the optimization of the experimental setup and the validation of the testing procedure. After that, the fatigue behavior of the joints will be tested in different aggressive environments. This study pointed out that it is possible to build a simple and low-cost setup for the study of fatigue corrosion behavior of dissimilar joints while exploiting in situ electrochemical measurements to follow the fatigue corrosion process.