Thermal/environmental barrier coating for silicon-containing materials

An article comprising:

• a substrate formed of a silicon-containing material;
• a mullite-containing first layer on the substrate;
• a second layer on the first layer, the second layer consisting essentially of barium strontium aluminosilicate;
• a third layer on the second layer, the third layer consisting essentially of yttria-stabilized zirconia and at least one material selected from the group consisting of barium strontium aluminosilicate, mullite and alumina;
• and
• a top coat of yttria-stabilized zirconia on the third layer.

A gas turbine engine component formed of a silicon-containing material and having a thermal/environmental barrier coating system on a surface thereof, the thermal/environmental barrier coating system comprising:

• a first layer on the surface and consisting essentially of mullite or a mixture of mullite and barium strontium aluminosilicate, the first layer having a thickness of about 75 to about 250 micrometers;
• a second layer on the first layer, the second layer consisting essentially of barium strontium aluminosilicate, the second layer having a thickness of about 125 to about 500 micrometers;
• a third layer on the second layer, the third layer consisting essentially of yttria-stabilized zirconia and one material selected from the group consisting of barium strontium aluminosilicate, mullite and alumina, the third layer having a thickness of up to about 500 micrometers;
• and
• a top coat of yttria-stabilized zirconia on the third layer, the top coat having a thickness of about 12.5 to about 1250 micrometers.