Microstructural evolution of plasma sprayed submicron-/nano-zirconia-based thermal barrier coatings

Microstructure Observation and Nanoindentation Size Effect Characterization for Micron-/Nano-Grain TBCs

“…Fewer and smaller inter-splat cracks and long cracks existed in nano-grain coating, that is to say the nano-grain coating had a finer columnar grain structure. However, the nano-grain coating had a significantly different feature compared with the micron-grain coating, because some unmelted particles were loosely distributed in the recrystallization zone (splats) as shown in Figure 4, which is consistent with literatures [5,[7][8][9]. These unmelted particles reserved the initial nanostructure of the agglomerated powder, as later confirmed by AFM (see Figure 5e).…”

“…In this article, Image-Pro Plus software (Media Cybernetics, Silver Springs, MD) was utilized to calculate porosity by quantitative image analysis. The final statistical result of porosity was the average value based on 10 cross-sectional images for an individual sample [8,9]. The statistical results showed that the porosities of micron-/nano-grain coatings were approximately 6.5% ± 0.2% and 5.1% ± 0.3%, respectively.…”

“…Studies have shown that improvement in physical, thermal, and mechanical properties of new materials can be attributed to improvement of microstructure when compared with conventional materials [4]. For plasma sprayed coatings, particle size of the feedstock powders [5][6][7][8] and spray parameters [9][10][11] have a great effect on the microstructure (such as porosity, micro-crack content, and grain size) of the coatings. Liang et al reported that the feedstock powders used for depositing nanostructured coating (particle size of agglomerated powders ranged in 30-50 µm, the size of nanoparticles inside the agglomerated powders varied from 50 to 80 nm) was smaller than the powders used for depositing conventional coating (particle size ranged in 60-100 µm), which contributed to the improvement of microstructure (such as reduction of grain size and contents of pores and micro-cracks) of the nanostructured coating [6].…”

“…Recently, a great deal of research with respect to the effect of microstructure on thermal properties such as thermal shock (oxidation) resistances [6][7][8]12,13] and thermal insulation [9,14], and mechanical properties such as hardness and modulus [5,[14][15][16][17][18][19][20][21][22] have been done. Wang et al found that the nanostructured zirconia coating possessed a better thermal shock resistance than that of the conventional zirconia coating [7].…”

Investigation of thermal shock resistant in three kinds thermal barrier cerium oxide coating (CeO2) with MCrAlY intermediate layer

“…In new systems, the bond coat is generally one of the MCrAlY (M = Ni and/or Co) coating group. At higher temperatures, such systems developed a thermally grown oxide (TGO) layer in the metal-ceramic interface, which protects the substrate metal surface from oxidation [8,9].…”