Distribution and arrangement of nanopores in an YSZ (7wt% Y 2O3-ZrO2)-thermal barrier coating (TBC) deposited by an electron beam-physical vapor deposition (EB-PVD) have been investigated by means of transmission electron microscopy. The YSZ-TBC deposited by the EB-PVD showed a typical columnar structure normal to the bond coat surface on the substrate. It has been generally believed that one column is a single crystal and grows continuously from the substrate. In the present study, however, it was found that each column consisted of a number of subcolumns with different misorientations and contained nanopores at the subcolumn boundaries. In addition to the nanopores at the subcolumn boundaries, nanopores with smaller size were observed within subcolumns, and were arranged periodically perpendicular to the growth direction of the subcolumns. Such arrangement and distribution of nanopores may be due to the misorientation of YSZ plate-like grains in the formation and coalescence processes of the YSZ subcolumns.
- Electron beam-physical vapor deposition
- Thermal barrier coating
- Yttria-stabilized zirconia
ASJC Scopus subject areas
- Materials Science(all)