Compatibility study of plasma grown alumina coating with Pb–17Li under static conditions

A novel plasma assisted tempering process has been developed to generate a stable alpha -Al sub(2)O sub(3) + FeAl coating on P91 steels. Hot dip aluminized P91 samples had been subjected to normalizing treatment in muffle furnace at 980 [degrees]C for 20 min followed by a glow discharge oxygen plasma assisted tempering treatment at 750 [degrees]C for 1 h. The plasma processing led to the formation of a stable alpha -Al sub(2)O sub(3) coating, while thermal tempering in muffle furnace led to formation of [theta]-Al sub(2)O sub(3) coating. Both the thermal and plasma tempered samples with alumina coating along with bare P91 samples were subjected to compatibility tests with Pb-17Li under static conditions at 550 [degrees]C for 1000 h. The extent of degradation of the samples was measured by weight loss method, X-ray diffraction and a cross-sectional examination with elemental studies using energy dispersive X-ray analysis. Plasma processed samples did not reveal any weight loss while thermally treated samples with metastable [theta]-Al sub(2)O sub(3) indicated 0.23 mg/cm super(2) weight loss and bare P91 steels indicated a weight loss of 7.3 mg/cm super(2).