Within a 50-mL tank, the electrolytic solution as described above received a voltage variation of 160 V initial tension at zero time and a final tension at the preset end-time for each group of samples. There was a gradual increase in voltage due to the maintenance of a fairly constant current at around 0.15 to 0.25 A. The electrolytic solution was periodically changed to prevent solution saturation. In group 2, the solution was changed every four anodizing processes, namely every four treated samples; in group 3, the solution was changed every two anodizing processes, namely every two treated samples; in group 4, the solution was changed every anodizing process, that is, every one treated sample. The experiment was conducted at room temperature.

Following completion of the anodizing process, the samples were quickly removed from the solution, washed with distilled water, and dried in open air. For a complete disposal of the anodic treatment, the samples were immersed in acetone altogether (Lot PA-55.317- Delaware Supplier, Porto Alegre/RS, Brazil) and taken to the ultrasonic tank (Ultra Sonic-1440 Plus—Odontobrás, Ribeirão Preto/SP, Brazil) for 10 min, washed again in distilled water, and finally air-dried.

All samples were coated with gold prior to scanning electron microscopy (SEM), which was performed with an EVO-LS15 (Zeiss). Observations were made at magnifications between ×500 and ×10.000 and limited to 20 μm for the ×500 and ×1.000 magnifications and to 2 μm for the ×5.000 and ×10.000 magnifications.

The analysis of salt deposition on the samples, occurring during the anodizing process, was performed using the energy-dispersive X-ray spectroscopy (EDS) system (energy-dispersive X-ray detector (EDD) or EDX), which is integrated with scanning electron microscopy unit.