Wear and Corrosion Performance of Al-Cu-Fe-(Cr) Quasicrystalline Coatings Produced by HVOF

High-velocity oxygen fuel coatings were produced using gas-atomized Al 62.5 Cu 25 Fe 12.5 and Al 67 Cu 20 Fe 5 Cr 8 powders onto a ferritic stainless-steel substrate, resulting in two similar microstructures, consisting mainly of quasicrystalline phases. The goal of this work was to evaluate the performance of the quasicrystalline coatings under standard wear and corrosion tests. The samples were characterized by x-ray diffraction and scanning and transmission electron microscopy. Wear and friction behavior of the coatings and substrate were assessed by pin-on-disk tests. Vickers microhardness was also measured. The corrosion resistance was assessed through electrochemical measurements performed in alkaline and acidic medium in the absence and in the presence of chlorides. The coefficient of friction of the quasicrystalline coatings were inferior to the substrate, particularly the Al-Cu-Fe coating, with values close to 0.1. The Al 62.5 Cu 25 Fe 12.5 alloy also showed the lowest specific wear rate, 1.7 × 10 −4 mm 3 /N m, among the materials tested. In the presence of chlorides, the chromium containing coating presented better corrosion resistance with less surface damage after testing. However, the corrosion rate of the coating samples was low in both chloride-free alkaline and acidic conditions. Both Al 62.5 Cu 25 Fe 12.5 and Al 67 Cu 20 Fe 5 Cr 8 coatings presented corrosion potential considerably lower than the substrate for all tested media, which may be interesting for cathodic protection.