High temperature oxidation resistance of 1.25cr-0.5mo wt.% steels by zirconia coating

A zirconia coating was applied to improve the oxidation resistance of 1.25Cr-0.5 Mo wt.% steels. A 8 wt.% yttria-stabilized zirconia coating was deposited by sol-gel technique. One problem with this method is that the hydrolysis of the organometallic precursors is faster than condensation, and the formation of precipitates is favored. Ethyl acetate was used to slow the hydrolysis rate in order to obtain a more continuous layer. The air oxidation behavior of the coating was studied at 600 °C and 700 °C by the continuous measurement of the weight gain. The microstructural characterization was performed by optical and scanning electron microscopy, and the composition was determined by energy dispersive spectroscopy (EDS). The weight gain of the 1.25Cr-0.5 Mo wt.% was diminished by about 70% compared to uncoated samples.