Patent ID: 7226668

Claim:
A thermally protected article, which comprises: 1. a metal substrate; 2. a bond coat layer adjacent to and overlaying the metal substrate; and 3. a thermal barrier coating comprising: a. an inner thermal barrier layer comprising from about 75 to about 99% of the thickness of the thermal barrier coating and being adjacent to and overlaying the bond coat layer, the inner layer comprising from about 95 to 100% of a ceramic thermal barrier coating material selected from the group consisting of zirconias and pyrochlores of general formula A 2 B 2 O 7 where A is a metal having a valence of 3+ or 2+ selected from the group consisting of gadolinium, aluminum, cerium, lanthanum and yttrium, and B is a metal having a valence of 4+ or 5+ selected from the group consisting of hafnium, titanium, cerium and zirconium, and wherein the sum of the A and B valences is 7; and b. a CMAS-protective outer layer comprising from about 1 to about 25% of the thickness of the thermal barrier coating and being adjacent to and overlaying the inner layer and having an exposed surface, the outer layer comprising: (1) a CMAS-reactive material in an amount up to 100% and sufficient to protect the thermal barrier coating at least partially against CMAS that becomes deposited on the exposed surface, the CMAS-reactive material comprising an alkaline earth aluminate, alkaline earth aluminosilicate or mixture thereof, wherein the alkaline earth is selected from the group consisting of barium, strontium and mixtures thereof; and (2) optionally a ceramic thermal barrier coating material.