Abstract
Multilayer thermal barrier coatings are being investigated for high temperature applications by employing a strain accommodating interlayer. Plasma sprayed coatings of nanostructured feedstock have shown promise in this direction. Layers of nanostructured yttria stabilized zirconia (nano–YSZ) and conventional YSZ were deposited on mullite substrates using the triple torch plasma reactor (TTPR), and on NiCrAlY coated steel substrates using the Praxair SG-100 plasma torch. The coatings were heat treated and the microstructure evaluated. Heat treating the samples lead to the formation of larger pores with a significant proportion of partially molten particles. The porosity evolved from the partial sintering of the nano-agglomerates. Porosity change during the sintering process was measured and the microstructure observed using electron microscopy. The nanostructured coatings were compared to conventional YSZ coatings.
