Thermal barrier coatings by electron beam-physical vapor deposition of zirconia co-doped with yttria and niobia

Synthesis and Characterization of Stabilized Zirconia Toughened Alumina (ZTA) Doped Niobium Pentoxide (Nb2O5)

“…4 (b), (c) and (d), the microstructure of doped ZTA samples distribution shows the same allocation as the undoped ZTA sample even with presence of niobium pentoxide particles. This is because the addition of Nb 2 O 5 does not change the microstructure that is only up to 6 wt% niobium pentoxide addition [12,13]. Lesser porosity with good particle distribution and sizes shown by ZTA0.5 and ZTA0.7 compared to pure ZTA sample and 0.3 wt% Nb 2 O 5 dopant.…”

On the performance and failure mechanism of thermal barrier coating systems used in gas turbine blade applications: Influence of bond coat/superalloy combination

“…Although the top coat is characterized by low thermal conductivity, it is further reduced by the presence of a high concentration of such voids, which act as centers of phonon scattering [7][8][9]. Along the cross-section, the grains with columnar morphology are aligned normal to the substrate surface, which satisfies the requirement of high resistance to thermal shock [7][8][9]. As can be seen, the top coat is adhered to the substrate by means of the thin layer of Al 2 O 3 developed by the bond coat during processing as described earlier.…”

“…For aeroengine applications, the top coat is applied by the technique of electron beam-physical deposition (EB-PVD) and plasma spraying is usually used in the case of land-based turbines. Recently, however, EB-PVD has increasingly been used in the land-based application because it produces coatings with higher resistance to thermal shock, smother surface and longer life [6][7][8][9].…”

Revestimentos para barreira térmica: evolução e perspectivas

“…As trincas são devidas às tensões residuais provocadas pela oxidação da camada de ligação metálica em altas temperaturas (formação e crescimento da TGO), devido à permeabilidade da camada cerâmica porosa, e às diferenças de expansão térmica cíclica (fadiga térmica no aquecimento e resfriamento dos componentes, durante o serviço), resultantes da diferença de cerca de 30 % no coeficiente de expansão térmica entre a zircônia parcialmente estabilizada e a camada de ligação metálica [2,3,4]. Diversas pesquisas têm sido realizadas na busca de solucionar estes problemas, envolvendo, inclusive, o conceito de revestimentos graduados [19,20], pré ou pós-tratamentos dos revestimentos [21,22,23] e adição de dopantes [24,25].…”