Thermal barrier coating protected by tantalum oxide and method for preparing same

Abstract

A thermal barrier coating for an underlying metal substrate of articles that operate at, or are exposed to, high temperatures, as well as being exposed to environmental contaminant compositions. This coating includes an inner layer nearest to the underlying metal substrate comprising a ceramic thermal barrier coating material, as well as an outer layer having an exposed surface and comprising tantalum oxide in an amount sufficient to protect the thermal barrier coating at least partially against environmental contaminants that become deposited on the exposed surface and optionally an intermediate layer between the inner and outer layers comprising alumina. This coating can be used to provide a thermally protected article having a metal substrate and optionally a bond coat layer adjacent to and overlaying the metal substrate. The thermal barrier coating can be prepared by forming the inner layer comprising the ceramic thermal barrier material, optionally forming the intermediate layer comprising the alumina over the inner layer, and then forming the outer layer comprising the tantalum oxide over the intermediate (inner) layer.