Microstructure and Thermal Properties of Nanostructured 4 wt.%Al2O3-YSZ Coatings Produced by Atmospheric Plasma Spraying

Abstract

Microstructure and phase composition of the nanostructured Al 2 O 3 doped YSZ coatings by atmospheric plasma spraying method have been characterized with XRD, TEM and SEM. The nanostructured 4AlYSZ coatings consist mainly of t-ZrO 2 , crystalline Al 2 O 3 phase is absent in the coatings and the grain size of the 4AlYSZ coating is about 65 nm. The APS 4AlYSZ coating is characterized by nanozones, dense area and voids. After doping, the coefficient of thermal expansion of YSZ is decreased to 10.928 3 10 26 /K. The addition of Al 2 O 3 has a great influence on decreasing the thermal conductivity of nano-YSZ, which is mainly caused by the point defect scattering and grain-boundary scattering. The lifetime of nanostructured 4AlYSZ coating is about 1000 cycles at 1100°C.

Hot corrosion, high temperature oxidation and thermal shock behavior of nanoagglomerated YSZ–Alumina composite coatings produced by plasma spray method

“…8(b) the peaks related to Al 2 O 3 could not be detected. Yu [19] and Lianga [20] neither detected Alumina phase in XRD patterns due to the solid solution of Alumina in Zirconia. The solubility of Al 2 O 3 in ZrO 2 could be up to 2 mol% at temperatures ≤1400°C, and slightly increases with the increase of temperature.…”

Thermal conductivity prediction in air plasma sprayed thermal barrier coatings containing multifarious defects

“…Based on the heat conduction theories of composite materials, various models have been recommended with different assumptions and approximations to estimate the thermal conductivity of TBC systems, as listed in Table 1 7–17 . However, as shown in Figure 1, the thermal conductivity estimated by these models deviates far from measured results reported here and in previous literature 18–23 …”

Adhesion strength and thermal shock properties of nanostructured 5La3TiYSZ, 8LaYSZ and 8CeYSZ coatings prepared by atmospheric plasma spraying

“…3. The top ceramic coats showed intrinsic defects, such as pores, little nano size particles and lamellar splat boundaries, which exhibited typical characteristic of nanostructured coating [19]. Three kinds of ceramic coats have similar microstructure.…”