Structural characteristics and tribological properties of an ultrafine-grained Al–40Si–5Fe coating prepared by supersonic plasma spraying

High silicon aluminum alloy coatings (HSAACs) are characterized by high surface hardness and excellent wear resistance, and the fineness has a significant impact on their properties. In this study, Al–40Si–5Fe coating was prepared by supersonic plasma spraying using Al–35Si–4Fe powder as raw material. The coating contains a variety of strengthening structures such as amorphous, nanocrystalline and supersaturated solid solution. The average hardness of the coating reached up to 465.3 ± 24.4HV 0.2 , which was much higher than that of the Al–Si alloys/coatings prepared by various processes. Under the test conditions, the wear mechanism of the coating was dominated by fatigue wear with slight abrasive wear, and the wear rate was 1.88 × 10 –4 mm 3 /N. A large amount of refined Si phase in the oxide film on the worn surface effectively prevented the cracking and spalling of the oxide film. Graphical abstract