Study on the negative effects of low sodium hexametaphosphate concentration on MAO coating

Abstract

In order to investigate the effect of electrolyte concentration on the wear resistance and corrosion resistance of the microarc oxidized ceramic coatings in a mixed electrolyte system, this study set up a silicate only electrolyte as the control group, and additionally set up a concentration gradient with the concentration of (NaPO3)6 as the variable, and prepared oxidized ceramic coatings on 1060 aluminum alloy. The surface morphology and microstructure of the coatings were observed by scanning electron microscopy, and the phase composition changes in the single electrolyte system and in the mixture were compared by X-ray diffraction mapping. The elemental composition and distribution of the prepared coatings under the mixture were also characterized by energy dispersive spectroscopy. Finally, the wear and corrosion resistance of the coatings were analyzed and studied by friction experiments and electrochemical results and the mechanism of the effect of the continuous addition of (NaPO3)6 on the coating properties was explained. The results show that the coating prepared at low concentration of (NaPO3)6 has poor tribological and corrosion resistance, even worse than the control group. In view of this phenomenon, the research is carried out and the corresponding explanation is made.