OXIDATION BEHAVIOR OF THERMAL BARRIER COATINGS MODIFIED BY LASER REMELTING

In this study, a bond coat (Ni-22Cr-10A1-1Y (wt%)) and a top coat (ZrO 2-7.5 wt% Y2O3) were deposited on 304 stainless steel by air plasma sp raying and then processed with either single laser remelting (SLR) or double laser remelting (DLR) treatment. Preheating specimens at 950 de grees C in the SLR treatment reduced depressions and the width of crac ks in the top coat. A recently developed DLR treatment, in which zirco nia powder in the form of a colloidal suspension was applied after SLR and then laser remelted again, helped to lower the extent of surface defects in the top coat significantly. Oxidation tests at 1200 degrees C indicated that the DLR specimens had a better oxidation resistance than the SLR and the plasma-sprayed specimens. (C) 1998 Published by E lsevier Science S.A.