Turbine engine shroud

In a gas turbine engine, a shroud comprising a plurality of arcuate segments disposed in end to end relationship to surround the tips of the rotor blades of the engine wherein each segment has a sealing surface which opposes the tips of the blades wherein the sealing surface is formed of an amphoteric refractory oxide matrix of material selected from ZrO.sub.2, Al.sub.2 O.sub.3, Ce.sub.2 O, ThO.sub.2 and HfO.sub.2 or mixture, a phosphate binding agent stable above about 1350.degree. C., and from 0 to 50% by weight of the matrix material of a stabilizer selected from Y.sub.2 O.sub.3, MgO, CaO, rare earth oxide or mixture and from 0 to 25% by weight of the matrix material of a filler.