Thermal barrier coating protected by infiltrated alumina and method for preparing same

摘要

A thermal barrier coating (22) for an underlying metal substrate (14) of articles (10) that operate at, or are exposed, to high temperatures, as well as being exposed to environmental contaminant compositions. This coating (22) includes a porous outer layer (30) having an exposed surface (34) and comprising a non-alumina ceramic thermal barrier coating material, as well as alumina infiltrated (42) within the porous outer layer (30) in an amount sufficient to protect the coating (22) at least partially against environmental contaminants that become deposited on the exposed surface (34). This coating (22) can be used to provide a thermally protected article (10) having a metal substrate (14) and optionally a bond coat layer (18) adjacent to and overlaying the metal substrate (14). The thermal barrier coating (22) can be infiltrated with the alumina by treating (42) the porous outer layer (30) with a liquid composition (38) comprising an alumina precursor and then converting the infiltrated alumina precursor to alumina.