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

A thermally protected article, which comprises:

• 1. a metal substrate;
• and
• 2. a thermal barrier coating comprising:
• a. a porous outer layer overlaying the metal substrate, the outer layer having an exposed surface and comprising a non-alumina ceramic thermal barrier coating material;
• and
• b. alumina infiltrated within the outer layer in an amount sufficient to protect the thermal barrier coating at least partially against environmental contaminants that become deposited on the exposed surface.

A method for preparing a thermal barrier coating protected by infiltrated alumina that overlies a metal substrate, the method comprising the steps of:

• 1. providing a thermal barrier coating overlaying a metal substrate, the thermal barrier coating including a porous outer layer having an exposed surface and comprising a non-alumina ceramic thermal barrier coating material in an amount up to 100%;
• 2. treating the outer layer with a liquid composition comprising an alumina precursor to infiltrate the outer layer with the alumina precursor in an amount sufficient to provide, when converted to alumina, at least partial protection of the thermal barrier coating against environmental contaminants that become deposited on the exposed surface;
• and
• 3. converting the infiltrated alumina precursor within the outer layer to alumina.