High Temperature Aging Behavior of Plasma Sprayed La2(Zr,Ce)2O7 Coatings

Three different Ce modified La2Zr2O7 powders (La2Zr2O7 (LZ), La-2(Zr0.7Ce0.3)(2)O-7 (LZ7C3), La-2(Zr0.3Ce0.7)(2)O-7 (LZ3C7)) were prepared by a co-precipitation method. The three coatings were prepared by a plasma spraying method. The coatings were aging treated at 1200 and 1300 degrees C for 100 h. The scanning electron microscopy, X-ray diffraction, transmission electron microscopy and other methods were used to compare the crystal structures of the powders, nano grain size, lattice constants, the high-temperature phase structure evolution and aging behavior of the coatings. The results show that LZ and LZ7C3 powders present a single pyrochlore structure, while LZ3C7 powder presents a single fluorite structure. As the Ce content increases, the powder, lattice constant increases. All three as-prepared coatings show fluorite structures. LZ and LZ7C3 coatings transform into pyrochlore structure after aging at 1200 and 1300 degrees C for 100 h. LZ3C7 coating maintains fluorite structure after aging at 1200 degrees C for 100 h, while it transforms into two phases (fluorite and pyrochlore structure) after aging at 1300 degrees C for 100 h. After aging at 1300 degrees C for 100 h, the three coatings exhibit different coating microstructures. After LZ coatings are sintered, micro holes are formed, LZ7C3 coatings remain microcracks structure, and many holes are formed in LZ3C7 coatings.