Porosity of Oxide Ceramic Coatings Formed by Micro-Arc Oxidation on High-Silicon Aluminum Alloys.

Autor: Dudareva, N. Yu., Kolomeichenko, A. V., Deev, V. B., Sitdikov, V. M.
Zdroj: Journal of Surface Investigation: X-Ray, Synchrotron & Neutron Techniques; Dec2022, Vol. 16 Issue 6, p1308-1314, 7p
Abstrakt: Oxide coatings formed by micro-arc oxidation (MAO) are usually considered to be quite dense in structure. However, in this work, we present studies that show that the porosity of coatings formed on AlSi26CuNiMg high-silicon aluminum alloy containing 26 wt % Si can reach 9.8–28.7%. The porosity is studied on images of cross sections obtained using scanning electron microscopy. A complete factorial experiment is implemented and a regression equation is obtained that shows the influence of the electrical parameters of the setup and of the electrolyte composition on the coating porosity. It is found that the porosity depends mostly on the concentration of KOH and considerably on that of Na2SiO3 in the electrolyte. Correlation analysis shows that an increase in the anode voltage reduces the porosity of the MAO coating, and the anode current does not have a significant effect on it. The absence of a close relationship between the thickness and porosity of the MAO coating is also found. In this work, the mechanism of porosity formation is proposed. It is assumed that the formation of closed pores occurs in the domain of superposition of the temperature fields from micro-arc/spark discharges. The superposition of temperature fields causes local melting of the previously formed coating, and pores are formed after solidification of the melt. The influence of the anode voltage on the porosity of the MAO coating is explained. [ABSTRACT FROM AUTHOR]
Databáze: Complementary Index
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