Porosity evaluation of aluminium oxide thin films influenced by variation of voltage and current intensity applied during the process of plasma ectylurea oxidation

Porosity on aluminium surfaces were controlled by pulsed plasma electrolytic oxidation. For this, it was used a variable pulsed voltage source up to 1500V and 2A. The samples were polarized anodically and placed in electrolyte sodium silicate. A voltage pulse with 70μs of width and a dependent height of the applied current. Pulse and electrolyte concentration were set and varying oxidation time and current intensity. The samples were characterized by diffraction of X-ray (XRD) and scanning electron microscopy (SEM). It was found that it is possible to control the size and distribution of pores varying current and oxidation time. In general these variables are proportional, except only for shortest current and longest oxidation time, which caused smaller pore size and higher porosity. These results are discussed in light of the dynamic oxidation and nucleation sites. (author)