Microstructure and properties of micro-arc oxidation films on SiCp/Al matrix composites in different electrolyte systems

Abstract

Micro-arc oxidation films were prepared on the surface of SiCp/Al matrix composites in (NaPO3)6, Na2SiO3-NaOH and NaAlO2-NaOH electrolyte.The microstructure and phase composition of the films were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD).The wear resistance and corrosion resistance of the substrate and films were analyzed by friction and wear test and electrochemical workstation. The results show that the uniform micro-arc oxidation films can be prepared in all the three electrolytes. The roughness and thickness of the film prepared in NaAlO2-NaOH is the largest. The phases of the films prepared in the three electrolytes are different. The microhardness of SiCp/Al matrix composites is improved by micro-arc oxidation, and the hardness of the film prepared in NaAlO2-NaOH reaches 1125HV. The friction coefficient of SiCp/Al matrix composites is reduced by micro-arc oxidation. According to the friction coefficient and wear condition, the film prepared in NaAlO2-NaOH has excellent wear resistance. The micro-arc oxidation film prepared in three kinds of electrolyte can improve the corrosion resistance of SiCp/Al matrix composites. The corrosion resistance of the film prepared in Na2SiO3-NaOH is excellent, the corrosion potential and current density of the film prepared in Na2SiO3-NaOH are -0.6122 V and 2.704×10-7 A·cm-2, respectively.

Keywords

• sicp/al matrix composite
• micro-arc oxidation
• microstructure
• wear resistance
• corrosion resistance