Abstract Aluminum alloys have been widely used in multiple applications, such as in civil construction and engine pistons. They are subjected to loads that may impair their mechanical properties. Thereby, this research aims to study the influence of anodization on the mechanical properties of alloy samples and evaluate the behavior of oxide films when subjected to tensile testing. The mechanical properties of specimens have been evaluated based on tensile and Knoop hardness tests, and strain, tensile strength, and modulus of elasticity of specimens have been determined based on the stress-strain curve. The morphology of oxide films was analyzed by scanning electron microscopy (SEM) and optical microscopy (OM). Results of anodized Al-Si alloys in both modes, i.e. pulsed and direct currents, were compared, and it was found that pulsed current was more efficient than direct current with respect to uniformity of the formed film, and that the anodization process can affect a few mechanical properties of samples. The tension testing results also revealed that the oxide film has been fractured perpendicularly towards traction. However, the oxide film hardness was not affected by the anodization mode (pulsed or direct currents). In addition, a heat treatment was efficient at improving the uniformity of anodic films.

Materials degradation due to simultaneous chemical and mechanical effects may occur under a variety of conditions. Galvanized and zinc-iron electrodeposited steels are widely used to protect automobile bodies against corrosion. In such applications, it is important to investigate the electrochemical and tribological behaviour of the coatings, in order to understand the behaviour of those surfaces in a tribological contact exposed to a corrosive environment. In the present paper, the evolution of open circuit potential, for both surfaces, was monitored during reciprocating sliding against an alumina pin in a 3% NaCl solution. The coatings are compared in terms of electrochemical behaviour by polarization tests, open circuit potential and friction coefficient during sliding; and loss of mass after sliding. The surface morphology, after sliding, was examined by SEM. Under the experimental conditions of the present study, the results found in terms of corrosion and wear resistance could be correlated to the differences in morphology, rugosity and composition of the two analysed surfaces.

The development of hybrids materials has been extensively investigated in recent years. The combination of a wide variety of compositions and production processes had permitted the use of these materials in different applications like coatings for corrosion protection of metals. In this work organic-inorganic hybrid materials have been prepared from the hydrolysis of tetraethylorthosilicate and silanol-terminated polidymetilmetoxysilane using a sol-gel process. These materials have been applied on galvanized steel and on steel electroplated with a ZnFe. In order to evaluate the degradation behavior of these coatings, electrochemical techniques (Electrochemical Impedance Spectroscopy and Potentiodynamic Polarization) were used. EIS data was fitted to an equivalent circuit from which the electrochemical parameters were obtained. Results show a good protective character of the hybrid films, when compared with uncovered specimens. The overall performance of the coating systems appears to be highly dependent on the kind of metallic coating applied to the steel.