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《矿物冶金与材料学报:英文版》
>Effects of heat treatment on the corrosion resistance of carbon steel coated with LaMgAl_(11)O_(19) thermal barrier coatings
Effects of heat treatment on the corrosion resistance of carbon steel coated with LaMgAl_(11)O_(19) thermal barrier coatings
LaMgAl_(11)O_(19) thermal barrier coatings(TBCs) were applied to carbon steels with a NiCoCrAlY bond coat by plasma spraying. The effects of heat treatment on the corrosion resistance of carbon steel coated with LaMgAl_(11)O_(19) TBCs were investigated in 3.5wt% Na Cl solution using polarization curves, electrochemical impedance spectroscopy(EIS), scanning electron microscopy(SEM), and X-ray diffraction(XRD). The results show that a large number of cracks are found in the LaMgAl_(11)O_(19) TBCs after the samples are heat-treated, including some through-thickness cracks. The corrosion forms of the as-sprayed and heat-treated TBCs are uniform corrosion and pitting corrosion, respectively. The as-sprayed TBCs exhibit three EIS time constants after being immersed for less than 7 d, and then a new time constant appears because of steel substrate corrosion. When the immersion time is increased to 56 d, a Warburg impedance(W) component appears in the EIS data. The EIS data for the heat-treated TBCs exhibit only two time constants after the samples are immersed for less than 14 d, and a new time constant appears when the immersion time is increased further. The heat treatment reduces the corrosion resistance of carbon steel coated with LaMgAl_(11)O_(19) TBCs. The corrosion products are primarily γ-Fe OOH and Fe3O4.
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