Multiphase Ceramic Coatings with High Hardness and Wear Resistance on 5052 Aluminum Alloy by a Microarc Oxidation Method

摘要

High-hardness and wear-resistant ceramic coatings were obtained on 5052 aluminum alloy by the microarc oxidation (MAO) process in silicate electrolytes with different nano additives (TiO2, Si3N4), and the effects of different nanoadditives on the microstructural and mechanical properties of the ceramic coatings were systematically studied. The microstructure results revealed that the nanoadditives could improve the thickness and compactness of the ceramic coatings. The X-ray diffraction results demonstrated that the nanoadditives were successfully incorporated into the MAO coatings and that some new phases of Si2N2O and TiN were formed, enhancing the comprehensive performance of the ceramic coatings. Furthermore, the distributions of elements determined from energy-dispersive X-ray (EDX) spectroscopy and cross-sectional images displayed a good homogeneity to support the excellent mechanical properties of the ceramic coatings. Therefore, the average microhardness, the full indentation force depth curves, the hardness and elastic modulus, and the H/E and H-3/E-2 ratios of the ceramic coatings with TiO2 and TiO2 + Si3N4 nanoadditives delivered a very high hardness, implying good antifriction properties. Moreover, the friction coefficients of the ceramic coatings also demonstrated their outstanding wear resistance. Finally, the corrosion resistance and electrochemical impedance spectroscopy results further revealed the compactness of the ceramic coatings, indicating a high hardness and abrasion resistance.