Transmission electron microscopy study of thermal barrier coatings fabricated by electron beam-physical vapor deposition

Yttria stabilized zirconia (YSZ) film was deposited on to a stationary metal substrate by electron beam-physical vapor deposition (EB-PVD) at 850°C. The film was characterized using transmission electron microscopy and scanning electron microscopy. The film was composed of inverted triangular-based pyramidal grains (T-grains) and inverted diamond-based pyramidal grains (D-grains). The T-grains were aligned in the 〈111〉 direction and D-grains in 〈110〉 perpendicularly to the substrate. Furthermore, striated lines of nano-pores, which should be strongly related to the thermal conductivity of the film, were observed in each YSZ grain. The pores were oriented in the 〈110〉 in the (111) plane and distributed across {114̄} planes in the YSZ grains aligned in the 〈111〉 (T-grains). In the YSZ grain aligned in the 〈110〉 (D-grains), the pores were oriented in the [1̄10] and the [001] directions in the (110) and distributed across the (001) and (1̄10).