Research progress in the application of optical emission spectroscopy in metal microarc oxidation surface treatment

Abstract

Spark discharge phenomenon in solution is a typical characteristic in metal microarc oxidation (MAO) surface treatment, and the optical emission spectroscopy (OES) is an effective way of characterizing micro-discharge optical emission spectra and studying the MAO mechanism. In this paper, the research status of OES analyses in MAO process of Al, Mg, Ti and their alloys was reviewed, the calculation principle of electron temperature and density in microarc plasma discharge channels was introduced, and the influence of the plasma discharge behavior on the microstructure of MAO coatings at different metals, electrical parameters and electrolyte solutions was evaluated. Furthermore, the different discharge models on the basis of OES analyses were also discussed. The plasma temperature in microarc discharge zone for different metals calculated from OES was in the range of 3000 - 10000 K, which provided the evidence for the growth mechanism of ceramic coatings enhanced by quick molten-solidification process in discharge channel.

Keywords

• microarc oxidation
• optical emission spectroscopy
• discharge mechanism
• electron temperature