Thermal/environmental barrier coating with transition layer for silicon-comprising materials

An article comprising:

• a) a substrate formed of a silicon-comprising material;
• b) an environmental barrier layer overlying the substrate;
• and
• c) a transition layer overlying the environmental barrier layer, the transition layer comprising zirconia or hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium and lanthanide metals;
• and a low CTE oxide selected from the group consisting of niobia and tantala;
• and mixtures thereof;
• and
• d) a top coat overlying the transition layer, the top coat comprising zirconia or hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals, and mixtures thereof;
• wherein the transition layer comprises sublayers, a first sublayer contacting the environmental barrier layer and comprising niobia and/or tantala, and a second sublayer contacting the topcoat and having a substantially uniform composition of yttria-stabilized zirconia and/or yttria-stabilized hafnia.

An article as comprising:

• a) a substrate formed of a silicon-comprising material;
• b) an environmental barrier layer overlying the substrate;
• and
• c) a transition layer overlying the environmental barrier layer, the transition layer comprising zirconia or hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals;
• and a low CTE oxide selected from the group consisting of niobia and tantala;
• and mixtures thereof;
• and
• d) a top coat overlying the transition layer, the top coat comprising zirconia or hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals, and mixtures thereof;
• wherein the transition layer is compositionally graded and has a decreasing concentration of niobia and/or tantala and an increasing concentration of yttria-stabilized zirconia and/or yttria-stabilized hafnia in a direction away from the environmental barrier layer, and consists essentially of yttria-stabilized zirconia and/or yttria-stabilized hafnia at an interface of the transition layer with the top coat.

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

• a) an environmental barrier layer overlying the substrate and having a thickness of from about 25 to about 500 micrometers;
• b) a transition layer overlying the environmental barrier layer, the transition layer having a thickness of from about 25 to about 500 micrometers and comprising hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals;
• and a low CTE oxide selected from the group consisting of niobia and tantala;
• and mixtures thereof, and
• c) a top coat overlying the transition layer, the top coat having a thickness of from about 12.5 to about 1250 micrometers and comprising zirconia or hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals, and mixtures thereof.

A method for preparing a thermal/environmental barrier coating system on a substrate formed of a silicon-comprising material, said method comprising:

• a) forming an environmental barrier layer overlying the substrate and having a thickness of from about 25 to about 500 micrometers;
• b) forming a transition layer overlying the environmental barrier layer, the transition layer having a thickness of from about 25 to about 500 micrometers and comprising hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals;
• and a low CTE oxide selected from the group consisting of niobia and tantala;
• and mixtures thereof;
• and
• c) forming a top coat overlying the transition layer, the top coat having a thickness of from about 12.5 to about 1250 micrometers and comprising zirconia or hafnia stabilized with an oxide of a metal selected from the group consisting of magnesium, calcium, scandium, yttrium, and lanthanide metals, and mixtures thereof.