Oxidation Behavior of Three Different Ni-Cr Coatings in 630℃/25 MPa Supercritical Water
Oxidation behavior of FB2 steel for steam turbine and FB2 steel coated with three differ-ent coatings was comparatively investigated in 630℃/25 MPa supercritical water(SCW).The three coat-ings are supersonic flame spraying Ni-Cr coating(SFS-NiCr),glass shot peened SFS-NiCr and emery belt grinded SFS-NiCr.Their oxidation mass change was intermittently measured by electron balance,while their microstructure and phase composition were characterized by means of SEM,XRD and XPS before and after oxidation test.Results show that the oxidation kinetics curve of FB2 material deviated from the parabola due to the spallation of the formed oxide scale during the oxidation process.The oxida-tion kinetics curves of coatings prepared by different processes seriously deviated also from the parabo-la.A double-layered oxide scale formed on FB2 steel,consisting of an Fe-rich outer Fe3O4,Fe2O3 and a Cr-rich inner oxide layer.The oxide scale formed on the three coatings are mainly composed of chromi-um-rich oxide.The phase composition of the oxide scales formed on FB2 steel and the three coatings changed with the increase of oxidation time.Finally,the oxidation mechanism of FB2 steel and three coat-ings in supercritical water was discussed.
coatingoxidationsupercritical wateroxidation mechanismoxide film
NETL
NSTL
万方数据
维普
