Microstructural, Mechanical and Thermal Behavior of EB-PVD Deposited Multilayered YSZ and Lanthanum Zirconate Coatings for Thermal Barrier Applications

Microstructural, mechanical and thermal behavior of EB-PVD deposited multilayered YSZ and lanthanum zirconate coatings for thermal barrier applications S. K. Mishra1K. Shravan Kumar1, S. Bysakh2, M. Srimani2 and L.C. Pathak1 1CSIR-National Metallurgical Laboratory Jamshedpur-831007 India, 2CSIR-Central Glass and Ceramic Research Institute, Kolkota, India *Email: skm_smp@yahoo.co.in; telephone no.:91-657-2345256, Fax: 91-657-2345213 ABSTRACT: Yttria stabilized zirconia (YSZ) is an established TBC coatings with low thermal conductivity relatively high thermal expansion coefficient and chemical inertness in combustion atmospheres. However, for long term application above 1473K, YSZ shows phase transformation, which is detrimental. The improvement of engine performance require materials stable above 1473 K. To overcome research activities have increased for new high temperature materials to have high engine efficiency and prolonged life such as Al2O3, TiO2, mullite, CaO/MgO+ZrO2, CeO2 +YSZ, lanthanum aluminate, zircon, metal-glass composite, garnet (Y3AlxFe5?xO12) and zirconium phosphate ((Ca/Mg)Zr4?(PO4)6) are tried for TBC applications. Lanthanum Zirconate (La2Zr2O7) (LZ) is considered to be one of the promising TBC material and has already attracted great attention due to its encouraging thermophysical properties. LZ is excellent high temperature material for long term application above 1473 K without any phase transformations, where cubic pyrochlore structure is stable up to its melting point (2573 K). Nanocrystalline and layered matrix is supposed to have low thermal conductivity due to presence of large numbers of grain boundaries with enhanced phonon interaction compared to single crystal. The EB-PVD with the technological advancement are becoming economically feasible and favorable process; showing superior quality and reduction of thicknesses for all the layers are possible without affecting the thermal barrier efficiency. The present study will focus on thermal, microstructural and mechanical behavior of layered LZ/YSZ coatings by EBPVD and structure property correlation shall be attempeted studied through HRTEM, FEGSEM, mechanical & deformation behavior through nanoindentation on Ni base super alloys.