Patent ID: 8124252

Claim:
A system comprising: a blade track or blade shroud comprising: a substrate, an environmental barrier coating (EBC) formed over the substrate, wherein the EBC comprises at least one of mullite, barium strontium alumina silicate, barium alumina silicate, calcium alumina silicate, strontium alumina silicate, lithium alumina silicate, magnesium alumina silicate, or a rare earth silicate, and a multilayer, porous abradable coating formed over the EBC, wherein the multilayer, porous abradable coating comprises a plurality of layer pairs, and wherein each layer pair comprises a first layer including a rare earth silicate and a second layer including at least one of stabilized zirconia and stabilized hafnia; and a gas turbine blade comprising a blade tip, wherein the blade track or blade shroud and the gas turbine blade are configured so the blade tip contacts a portion of the multilayer, porous abradable coating during rotation of the gas turbine blade, and wherein the multilayer, porous abradable coating is configured to be abraded by the contact by the blade tip.