Characterization of Al2O3ZrO2 powders produced by electrohydrodynamic atomization

Air-plasma-sprayed thermal barrier coatings that are resistant to high-temperature attack by glassy deposits

“…Here we have demonstrated that the conventional method of APS can be used to deposit tetragonal YSZ TBCs with 20 mol.% Al 2 O 3 and 5 mol.% TiO 2 in complete solid solution, even when these oxides are expected to have little or no solubility in YSZ [42,43]. This extended solubility is attributed to the atomic-level mixing of the constituent elements in the chemically prepared powder feedstock and the rapid processes involved in the APS method that kinetically suppress any precipitation [44,45].…”

“…(1), l C is estimated at $8.6 lm. It is important to note that due to the extremely limited equilibrium solubility of Al in ZrO 2 [42,43], significant coarsening of the a-Al 2 O 3 precipitates is unlikely to occur during prolonged high-temperature exposure under actual engine conditions, assuring requisite thermal stability. Furthermore, this smallness of the a-Al 2 O 3 precipitates is not only important for preventing microcracking but also for assisting in long-term CMAS-attack resistance, as discussed below.…”

Development of Intermixed Zones of Alumina/Zirconia in Thermal Barrier Coating Systems

“…However, if the alloy was preoxidized to form a-Al 2 O 3 prior to TBC deposition, no intermixed zone formed. This was explained as resulting from the dissolution of zirconia in the transition halumina, which has a significant solubility for zirconia, [7] and the reprecipitation of zirconia as the h transformed to a. It was also argued that the dissolution of Zr (and Y) in h further delays its transformation to a, enabling the mixed zone to grow to a thickness larger than that expected from the transient alumina growth on NiCrAlY absent the TBC.…”

Dense Amorphous Zirconia–Alumina by Low‐Temperature Consolidation of Spray‐Pyrolyzed Powders

“…On the other hand, conditions that allow the desired metastable phase or nanometric grain size to be retained may not be adequate for complete densification. In the present study, the understanding of metastable phase synthesis and characteristics 3,[21][22][23][24][25][26] was applied to the hotpressing of amorphous ZrO 2 -Al 2 O 3 powders produced by spray pyrolysis in order to identify a pressure-temperature window in which consolidation would be possible without losing the metastable amorphous phase.…”