Microstructure and Properties of Air Plasma Sprayed Sm_2Zr_2O_7 Coatings

Rare-earth zirconates with a pyrochlore structure have attracted great attention for potential application in thermal barrier coating systems.In the present work,Sm2Zr2O7 coatings were deposited by atmospheric plasma spraying technology.Their microstructure,thermo-physical and mechanical properties were examined,and com-pared with that of 8wt% Y2O3 stabilized ZrO2 coatings which was deposited under the same plasma spraying condi-tions.X-ray diffraction result shows that the as-sprayed Sm2Zr2O7 coating exhibits a defective fluorite structure.The thermal conductivity of Sm2Zr2O7 coating measured at 800℃ is 0.44W/(m.K),about 40% lower than that of 8wt% Y2O3 stabilized ZrO2 coating,but the expansion coefficients of both coatings are similar.The Sm2Zr2O7 coat-ing exhibits lower bending strength,microhardness and elastic modulus compared with 8wt% Y2O3 stabilized ZrO2 coating.