Microstructure of oxides in thermal barrier coatings grown under dry/humid atmosphere

The microstructure of thermally grown oxide (TGO) in thermal barrier coatings (TBCs) oxidized under dry/humid atmosphere at 1100 °C has been characterized by transmission electron microscopy. A thin and continuous oxide layer is formed in the as-deposited TBCs produced by electron beam physical vapor deposition. The TGO formed in dry atmosphere consists of an outer layer of fine α-alumina, zirconia grains and an inner layer of columnar α-alumina grains. However, a small amount of spinel is observed in the TGO under humid atmosphere. The presence of water vapour promotes the formation of spinel.

The presence of water vapor promoted the formation of spinels in the TBC.Figure optionsDownload as PowerPoint slideHighlights
► Thermal barrier coatings are produced by electron beam physical vapour deposition.
► Oxidation behaviour of the coatings at 1100 °C has been investigated in dry/humid O2.
► Thermally grown oxides formed in the coatings are characterized.
► The presence of water vapour promotes the formation of spinel in the TBCs.