Electrochemical behavior of low-pressure plasma-sprayed Al-Cu-Fe-Cr quasicrystalline coating

Al-Cu-Fe-Cr quasicrystalline coating was deposited on a substrate of stainless steel by low-pressure plasma spraying (LPPS) method. The corrosion behavior of such coating was studied by polarization in 1 mol/l H2SO4 and 0.1 mol/l NaOH solutions at room temperature. The polarization curve shows that LPPS Al-Cu-Fe-Cr quasicrystalline coating can turn to passive state both in 1 mol/l H2SO4 solution and in 0.1 mol/l NaOH solution. The corrosion resistance of the coating is poorer than that of bulk quasicrystal in 0.1 mol/l NaOH solution. Also in strong alkaline solution the corrosion resistance of the coating is much poorer than single-phase austenitic stainless-steel 1Cr18Ni9Ti. In the later period of polarization, the Al2O3 layer formed on surface of the coating is destroyed by localized corrosion.